Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana Use and Its Effects

US National Commission on Marihuana and Drug Abuse

Table of Contents
I. Marihuana and the Problem of Marihuana
Origins of the Marihuana Problem
The Need for Perspective
Formulating Marihuana Policy
The Report
II. Marihuana Use and Its Effects
The Marihuana User
Profiles of Users
Becoming a Marihuana User
Becoming a Multidrug User
Effects of Marihuana on the User
Effects Related to Pattern Use
Immediate Drug Effects
ShortTerm Effects
Long Term Effects
Very Long Term Effects
III. Social Impact of Marihuana Use
IV. Social Response to Marihuana Use
V. Marihuana and Social Policy
Drugs in a Free Society
A Social Control Policy for Marihuana
Implementing the Discouragement Policy
A Final Comment
Ancillary Recommendations
Legal and Law Enforcement Recommendations
Medical Recommendations
Other Recommendations
Letter of Transmittal
Members and Staff
History of Marihuana Use: Medical and Intoxicant
II. Biological Effects of Marihuana
Botanical and Chemical Considerations
Factors Influencing Psychopharmacological Effect
Acute Effects of Marihuana (Delta 9 THC)
Effects of Short-Term or Subacute Use
Effects of Long-Term Cannabis Use
Investigations of Very Heavy Very Long-Term Cannabis Users
III. Marihuana and Public Safety
Marihuana and Crime
Marihuana and Driving
Marihuana - Public Health and Welfare
Assessment of Perceived Risks
Preventive Public Health Concerns
Marihuana and the Dominant Social Order
The World of Youth
Why Society Feels Threatened
The Changing Social Scene
Problems in Assessing the Effects of Marihuana
Marihuana and Violence
Marihuana and (Non-Violent) Crime
Summary and Conclusions: Marihuana and Crime
Marihuana and Driving
History of Marihuana Legislation
History of Alcohol Prohibition
History of Tobacco Regulation
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The National Commission on Marihuana and Drug Abuse

Marihuana - A Signal of Misunderstanding.

Chapter II

marihuana use and its effects

"Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passions, they cannot alter the state of facts and evidence." John Adams (1770)

The ultimate objective of the Commission is to evaluate the total impact of actual and potential marihuana use on contemporary American society. This endeavor involves three phases: first, an evaluation of the nature and scope of contemporary American marihuana use; second, a careful reevaluation of the pharmacological effects of the drug on the human body with special emphasis on the drug's capacity to alter or modify behavior; and third, an evaluation of the impact of marihuana use on society. This chapter deals with the first and second phases, and Chapter Three deals with the third.

The Marihuana User

Cannabis has been used widely for many centuries in nonindustrialized countries of Asia and Africa. Today, as in earlier years, use of drug is concentrated primarily among lower socioeconomic groups. in these countries, the practice is estimated to be confined to a tenth of the lower socioeconomic, male population. Although such use of the drug is well-established, it offers little direct comparison with the American experience.

Although the commercial, industrial and therapeutic value of the hemp plant was widely recognized and exploited in the United States from the earliest days of its history, knowledge and use of its intoxicating and psychoactive properties remained largely unknown until about 1900.

At that time, the custom of smoking marihuana was generally limited to groups of Mexican itinerant workers in the border states of the Southwest. By 1910, marihuana use began to emerge in other southern states and cities, particularly New Orleans, and in the port cities along the Mississippi River. In time, these cities became distribution centers for enterprising sailors. From there, marihuana use spread cross-country to other urban centers, mining camps, railroad construction sites, farm labor camps, "bohemian" communities of artists and jazz musicians, and various other groups outside the mainstream of American society.

Recently, of course, use of the drug has spread to young, white, middle class groups and especially to high school and college populations.


On the basis of the Commission-sponsored National Survey, we have concluded that contemporary marihuana use is pervasive, involving all segments of the U.S. population. The Survey estimated that about 24 million Americans over the age of 11 years (15% of the adults 18 and over, and 14% of the 12-17 year olds) have used marihuana at least once, referred to in this Report as ever-users. Until recently twice as many males as females had used it; the most up-to-date studies of high school students, college-age individuals, and young adults carried out by the Commission indicate that this sex differential appears to be diminishing. In many youthful populations use is almost equally distributed between males and females.

Marihuana use does not appear to vary significantly by race. With respect to the religious affiliation of the users, Jews and Catholics appear to be slightly overrepresented as compared to Protestants.

Usage is highest in cities, towns, and suburbs but not uncommon in rural areas. States in the Northeast and West have considerably higher rates of use than have the North Central states, which in turn have significantly higher rates than those in the South.

Use is found in all socioeconomic groups and occupations, though slightly more predominant among persons with above-average incomes. A New York survey of the state's general population indicated that ever-use as well as regular use is almost equally prevalent among sales workers, clerical workers, skilled, semiskilled and unskilled workers, managers, owners, professionals and technical workers.

At the same time, the incidence of use seems to vary according to educational attainment. Among all adults not now in school, 5% of those with an eighth grade education or less have used the drug, contrasted with 11% of those who completed some high school, 14% of those who graduated from high school, 25% of those who completed some college and 21 % of those who graduated from college.

Age is presently one of the most significant correlates of marihuana use. Among the total population, those who have tried or used marihuana at least once, termed ever-users, are heavily concentrated in the 16-25 age bracket. Of all the ever-users, about half are in this group. At the same time, however, we should emphasize that use is by no means confined to teenagers and young adults.

The proportion of individuals in different age groups who have used marihuana is indicated in Figure 1.

The incidence of use is greatest among young people: 27% of the 16-17 year olds, 40% of the 18-21 year olds, and 38% of the 22-25 year olds have tried marihuana; at the low extremes, 6% of the 12-13 year olds and 6% of the over-50 generation have used the drug.

Among those now in school, incidence also seems to rise with increasing school level: Ever-users represent 44% of those persons now in college or graduate school; 30% of high school juniors and seniors; 17% of freshmen and sophomores; and 8% of students in junior high school.

At the same time, the use of the drug among adults is by no means confined to college students. Even among the 18-25 year olds, 75% of the ever-users are not now in school.

The initial patterns of contemporary marihuana use appear to be shifting; there is a trend toward increased use among college students as well as non-college students. Non-student users now span social class, income level and occupational classification. In addition, the proportion -of users increases during the teens, peaks during the young adult years and then falls off rapidly (Figure 1).

Having described the incidence of any use of marihuana ever, and demographic characteristics of the 24 million Americans who have tried the drug, we recognize the need to place this information into perspective. The policymaker must also be concerned with the patterns of use: frequency, amount consumed at each smoking, and duration of use.


The most striking of the use patterns revealed in the National Survey is that 41 % of the adults and 45 % of the youth who have ever used marihuana reported that they no longer use the drug. Twenty-nine percent of the adults and 43% of the youth reported that they are still using marihuana (see Table 1). When asked why they bad terminated use, the overwhelming majority of adults (61%) specified, among other reasons, that they had simply lost interest in the drug.


Percent of ever-users

Frequency Adults Youth Designation

(18 and (12-17)


Have used marihuana but no longer 41 45

u se. lExperimenters.

Once a month or less 9 15

2-3 times pet month 8 10 Intermittent users.

Once per week 4 9 @

Several times per week 5 4 Moderate users.

Once daily 1 1 1

More than once daily 2 4 Heavy users.

No answer 30 12

These data indicate that at least 41% of the adults and 45% of the youth have used marihuana but have -discontinued use; 9% of the adults and 15% of the youth use the drug sporadically, once a, month or less. These persons can be characterized as experimental marihuana users.*

To ensure an understanding of this section of the Report, some definitions are required at this juncture. In this report, the Commission employs the following designations:

Frequency of Use

Experimental-At least one trial to once a month or less.

Intermittent-Two to 10 times monthly.

Moderate-11 times monthly to once, daily.

Heavy-Several times daily.

Very Heavy-Almost constant intoxication with potent preparations; brain rarely drug free.

Duration of Use

Short Term-Less than two years.

Long Term-Two to 10 years.

Very Long Term-Over 10 years.

Twelve percent of the adults and 19% of the youth who have ever used marihuana can be designated intermittent users; they continue to use the drug more than once a month, but less than several times a week, probably on weekends. Six percent of the adults and five percent of the youth are moderate users who continue to use marihuana several times a week to once daily.

Finally, 2% of the adults and 4% of the youth who have ever used marihuana are heavy users: they use the drug several times daily. A very small fraction of these heavy users may be very heavy users, who are intoxicated most of their waking hours and probably use very potent preparations of the drug.

In addition to frequency, duration of use is an important variable in discussing use patterns and especially when considering drug effects. Most users in this country have smoked the drug over a short term, that is, less than two years. Others have used the drug over a long term, two to 10 years. Very few Americans can be considered very long term users, that is, over 10 years.

Another important element of use is the amount of marihuana used on each occasion. Most intermittent and moderate users average about one-half to one cigarette per occasion, usually at night. Most heavy users smoke at least one to two cigarettes an occasion, with a few using as many as five consecutively.

As this brief description of use patterns suggests, marihuana use and the marihuana user do not fall into simple, distinct classifications. Although it is possible to sketch profiles of various marihuana-using populations, no valid stereotype of a marihuana user or non-user can be drawn. The spectrum of individuals who use or have used marihuana varies according to frequency, intensity and duration of use. It is meaningless to talk of "the marihuana user" or "marihuana use" without first clarifying descriptive data.

*All respondents for the National Survey were asked to complete a self administered questionnaire. This instrument covered many sensitive areas, including a series of items on personal experience with marihuana and other drugs. Given the nature of the questions, the contractor took every precaution to insure that the interviewee responded honestly and that his responses were kept strictly confidential. Even the interviewer who orally administered the rest of the Survey was not permitted to view the written instrument.

One of the inevitable costs of such confidentiality is the risk that a certain percentage of respondents would not complete one or more of the questions. Where a significant number of questions remained unanswered, the questionnaire was not tabulated at all. However, in 30%, of the otherwise complete questionnaires, the adult respondents who had ever used the drug did not answer the question, "On the average, about how often do you use marihuana at the present time?"

Concerned about the meaning of this non-response rate, the, Commission directed the contractor to conduct a detailed analysis comparing the non-respondents with all respondents and with those individuals who had never used marihuana at all. On the basis of this analysis, we are confident that the overwhelming majority, if not all, of the non-respondents are experimenters.

In the flrst place, the demographic characteristics of the non-respondents coincide closely with those of the non-users and less frequent users. Very few of the young adults, where more frequent use is concentrated, failed to respond.

Secondly, the non-respondents are disproportionately located in the geographic regions where use was least prevalent and least frequent. For example, 50% of the ever-users in the North Central region failed to respond, compared to 71% in the West. Yet only 5% of the ever-users in the North Central region continue to use the drug more than once a week, compared to 21% in the West; and less than .5% of the ever-users in the North Central region use the drug more than once a day, as compared to 4% in the West.


Several studies by the Commission and many other recent college and high school surveys have elucidated a variety of personality types or categories of marihuana users. These profiles relate primarily to the patterns depicted above and to the meaning of marihuana use for various individuals. Essentially we will describe a continuum with much overlapping among the categories. The reader should understand that group identification is at best a hazardous occupation; the traits described are not exclusive to marihuana users. A much larger number of individuals who have not used the drug can be similarly described.

Experimental Users

The first and by far the largest group has been designated as "experimenters" because of their extremely infrequent or non-persistent marihuana usage. Experimentation with the drug is motivated primarily by curiosity and a desire to share a social experience. These experimenters are characteristically quite conventional and practically indistinguishable from the non-user in terms of life style, activities, social integration, and vocational or academic performance.

Disciplined, optimistic, and self-confident, experimenters appear to be as conventional, responsible, goal-oriented and orderly as non-users.

Intermittent Users

The intermittent users are motivated to use marihuana for reasons similar to those of the experimenters. They use the drug irregularly and infrequently but generally continue to do so because of its socializing and recreational aspects. For the intermittent user, marihuana often contributes to the establishment and solidification of close social relations among users similarly inclined. The individual has a sense of belonging to an intimate group.

Investigations of behavioral aspects of marihuana smoking clearly demonstrate that marihuana smoking is a social activity, believed by intermittent users to enhance the enjoyment of shared activities, especially music, art, films and food.

In a Commission-sponsored study to determine the effects of repeat doses of marihuana, under free access conditions, the subjects smoked almost exclusively in groups. A certain number of these individuals tended to share much of their leisure time in common activities, and marihuana, smoking was the focal activity around which other types of social interactions revolved, such as conversation, watching TV, listening to music and playing games. The intermittent users studied exhibited an increased sense of well-being, relaxation, and friendliness during these activities. They were more inclined to seek and emphasize the social rather than personal effects of the drug.

Intermittent marihuana users, like the experimenters, are generally conventional in most respects. They are more liberal politically and socially and they tend to stress education for personal improvement rather than for recognition or high grades. Like many non-users, these individuals are likely to be self-expressive, intellectually and culturally oriented, creative, and flexible. Placing a high value on experimentation and responsible, independent decision-making, they often manifest a desire to search for new experiences, resulting in some behaviors which depart from the norms of the larger society. Often accompanying their search is a sense of uncertainty about the future.

Moderate and Heavy Users

The final groups of marihuana users are the moderate and heavy users. This range is wide and includes individuals who use marihuana more than 10 times a month to several times a day. Practically all of the American research effort to date has focused on the large majority of individuals who use less often, that is, the experimental and intermittent users. Consequently, not enough is known about characteristics and behavior of the moderate and the heavy users, so it is difficult to distinguish accurately between the two groups. We suspect however that the moderate users share traits with both the intermittent and the heavy users. Having already discussed the intermittent group, we will now turn to the characteristics of the heavy group.

Heavy users seem to need the drug experience more often. Their initial and continued marihuana use is motivated not only by curiosity and an urge to share a social experience but also by a desire for "kicks," "expansion of awareness and understanding," and relief of anxiety or boredom.

Generally, the heavy marihuana user's life style, activities, values and attitudes are unconventional and at variance with those of the, larger society. These individuals are more pessimistic, insecure, irresponsible, and nonconforming. They find routine especially distasteful. Their behavior and mood are restless and uneven.

Heavy users place particularly strong emphasis on impulsive response in the interest of pleasure-seeking, immediate gratification, and individual expression. They tend to evidence social and emotional immaturity, are especially indifferent to rules and conventions, and are often resistant to authority. However, several surveys have also revealed that they tend to be curious, socially perceptive, skillful and sensitive to the needs of others, and possess broadly based, although unconventional, interests.

The Boston free-access study permitted the Commission to observe a group of individuals whose life styles, activities, values and attitudes are representative of a segment of the unconventional youthful subculture. The month-long period of controlled study during the fall prevented the participation of individuals who were married, steadily employed, or enrolled in school.

Individuals who smoked marihuana once a week or less were sought by the researchers but were exceedingly unusual among the population available for the study. Consequently, the group studies contrasted with the student and full-time working populations in which weekly marihuana use is more common. For this reason, the intermittent users studied appeared to be similar to, rather than different from, the moderate and heavy users studied. Both groups had used marihuana for an average of five years.

Under the study's confined conditions, participants tended to smoke more marihuana than they did "on the outside." The intermittent users, who by our definition averaged eight times a month under outside conditions, averaged three cigarettes a day during the study. The range was from one-half to six cigarettes daily.

The moderate and heavy users, who "on the outside" averaged 33 times a month, now averaged six-and-a-half cigarettes a day. The range was three-and-a-half to eight cigarettes. In discussing the Boston study, we will call this group "daily" users.

Smoking usually occurred at night, sometimes during the afternoon and only occasionally upon awakening. The intermittent and heavy users usually smoked one cigarette a session. The daily users were more likely to smoke more than one a session. A few individuals in the daily group could have been considered constantly intoxicated on a few occasions during the 21 -day period.

The mean age of the subjects studied was 23. Based on IQ testing, they were superior intellectually, although they had completed, on the average, only two-and-a-half years of college. Their job histories were rather erratic, characteristic of a pattern of itinerant living. The intermittent users -were from a middle or upper class background, while the daily users generally shared a lower socioeconomic status. Broken homes and instances of alcohol or drug abuse were more common in the family backgrounds of the daily users.

Alcohol was rarely used by the subjects. Use of hallucinogens and amphetamines was significantly more widespread and had begun earlier in the daily user group. In contrast to the intermittent group, the daily users almost uniformly reported that marihuana smoking produced relaxation, noting also increased alteration in perception or psychedelic-like effects. Similarly, they reported an increased sense of well-being, friendliness, carefreeness and decreased hostility. Additionally, the daily users appeared to demonstrate a moderate psychological dependence on the marihuana experience while the intermittent users demonstrated little or no psychological dependence.

Analysis of social-behavioral aspects of daily users' marihuana smoking clearly demonstrated that it is a pivotal social activity around which conversation, other personal interactions, and much of the users' lives revolve. Smoking almost exclusively occurred in groups and was the focal activity around which these groups formed. The daily users exhibited a readiness to take part in but not to initiate a smoking session.

In contrast to the intermittent users, all the daily users in a group smoked when marihuana was made available. Marihuana smoking appeared to be a primary means of reinforcing group solidarity. Yet these users were more inclined to seek the personal effects of the drug rather than the socializing effects sought by the intermittent users.

The social adjustment of the daily users, when judged from a traditional psychiatric standpoint, was impaired. Individuals tended to be more withdrawn and to interact less with each other than the intermittent users, regardless of the type of activity or state of intoxication. However, the daily users did appear to accommodate themselves better than the intermittent users to the effects of the intoxication on social interaction.

Despite a relatively high level of scholastic attainment and superior intelligence, many of the subjects were performing well below their intellectual capability, usually working at menial, mechanical or artisan tasks. They were not oriented toward achieving the traditional goals of the larger society.

Nonetheless, during the period of the Boston study, the subjects could not be characterized as displaying a general lassitude and indifference, carelessness in personal hygiene or lack of productive activity, all supposed to be characteristic of very heavy use. Even during the periods of heaviest marihuana smoking, they maintained a high level of interest and participation in a variety of personal activities, such as writing, reading, keeping up on current world events, and participating in athletic and aesthetic endeavors.

Additionally, all of the subjects maintained a desire to complete all aspects of the research study. Although they could be labeled 'underachievers" in terms of the traditional standards of the larger society, these individuals were motivated to pursue actively the interests and activities of their own subculture.

Generally, most studies which have been undertaken indicate that individuals who are heavy marihuana users cannot find a place for themselves in conventional society. Their heavy marihuana use may reflect and perhaps perpetuate their unconventionality while providing social acceptance in one of the non-conventional subcultures.

Very Heavy Users

The Commission's analysis of frequency, quantity and duration of marihuana use suggest that the United States is at the present time in a fortunate position. All of the studies available to the Commission have indicated that only a minute number of Americans can be designated as very heavy marihuana users. These studies uniformly indicate that chronic, constant intoxication with very potent cannabis preparations is exceedingly rare in this country.

The Commission believes that important distinctions must be made between the daily (moderate and heavy) American marihuana user and the very heavy hashish or charas user in other parts of the world where cannabis is widely cultivated and its use deeply ingrained. Many of the North African and Asian users do not employ the drug only as an intoxicant in the western sense. Instead, it is frequently used in "folk medical practice," in religious rites and as a work adjunct particularly in those occupations which are physically demanding, monotonous, unintellectual, and offer little possibility of advancement.

In these countries, very heavy use is typically associated with young males from a lower socioeconomic background. Nonetheless, use is more widespread among all ages and elderly chronic users are not uncommon.

Generally, these very heavy users consume high amounts of very potent preparations continually throughout the day so that they are rarely drug-free. These individuals evidence strong psychological dependence on the drug, requiring compulsive drug-taking. Clear-cut behavioral changes occur in these extreme cases. The very heavy User tends to lose interest in all activities other than drug use. A common element of the behavioral pattern is lethargy and social deterioration. Not surprisingly, these users have been held in low esteem and very heavy use has been subject to societal disapproval in almost all countries.


Our attempt to classify marihuana users is primarily for descriptive purposes. It does not imply that all individuals who resemble any of the categories are necessarily marihuana users. Nor is it implied that all marihuana users fit neatly or precisely into these slots. There is no "typical" marihuana user, just as their is no typical American. The most notable statement that can be made about the vast majority of marihuana users-experimenters and intermittent users-is that they are essentially indistinguishable from their non-marihuana using peers by any fundamental criterion other than their marihuana use.

But if most users and non-users of marihuana essentially are indistinguishable, why have some people chosen to use the drug and others not, and why have some people continued to use it and others not? An important part of the explanation is that use of marihuana, like all human behavior, occurs within specific social and cultural settings. The individual's biological characteristics and personality probably play an important role in determining the pattern his use will take. However, the cultural and social setting play a larger role in determining whether be will use it at all.

Numerous studies have demonstrated that the young person who chooses to use marihuana differs in some important sociological respects from his peer who does not choose to do so. These differences relate to his willingness to experiment with a drug, especially a forbidden one. in short, the process of becoming a marihuana user is not a " seduction of the, innocent" as is often portrayed. Based on interrelated familial, social and cultural factors, persons, especially young persons, who may choose to use marihuana can be predicted statistically.

Parental Influence

The decision to use marihuana is related to parental life style.

Parents provide the most important example of acceptable drug-taking behavior for their children. That marihuana users frequently have medicine-taking, cigarette-smoking, or liquor-drinking parents has been demonstrated. In a series of Canadian studies, grade and high school students who said their mothers took tranquilizers daily were three times more likely to try marihuana than the students who did not so report.

Beyond the influence of a drug-taking example, parents have the primary influence on their childrens' acquisition of skills, values and attitudes necessary to be mature and responsible adults. Many parents have oriented their children toward becoming independent, competent, educated, and adaptive adults.

Simultaneously, many young people observe in their parents' lives the trend toward shorter work periods, earlier retirement and increased emphasis on leisure time activities. It appears that the incidence of adolescent marihuana use is strongly correlated with this trend toward increased leisure time.

Situational Factors and Behavioral Correlates

All studies of the ever user, including the Commission-sponsored National Survey, have established that marihuana smoking is significantly correlated with a number of demographic variables. Males, college students, and residents of metropolitan areas, especially in the Northeast and West, are generally overrepresented in proportion to their percentage of the total population.

Among the behaviors statistically correlated with marihuana, use are radical politics, visits to psychiatrists, sexual freedom, and separate residences from parents. The most significant behavior seems to be use of legal drugs, especially alcohol and tobacco. Young people who choose to experiment with marihuana are fundamentally the same people, socially and psychologically, as those who use alcohol and tobacco. For example, in a study of high school youngsters, only 3% of all the nonsmokers in the sample had ever tried marihuana, compared with 50% of all the current cigarette smokers. Similarly, for alcohol drinking outside the family setting, only 2% of all the nondrinkers had tried marihuana, as compared to 27% of the drinkers. The National Survey tends to confirm the close association between marihuana use and cigarette smoking and alcohol use. Among all the adults sampled in the Survey, 71% had smoked cigarettes and 39% are current smokers. Similarly, of adult non-marihuana users, 70% have smoked cigarettes and 38% are current smokers. These percentages increase somewhat for marihuana users: 87 have smoked cigarettes and 54% are current cigarette smokers.

In regard to alcohol consumption, 40% of all the adults sampled indicated that they had not consumed beer or bard liquor in the 30 days prior to the survey. Marihuana users tended to have consumed alcohol more often than non-marihuana users (Table, 2).


1-4 5-10 11 or No

0 days days days more answer


Percent of nonmarihuana users. . 45 19 6 7 21

Percent of marihuana users...... 26 30 12 8 24

Social Group Factors

One of the most influential factors in determining behavior in contemporary America among adolescents and young adults is peer group influence. Knowing other people who use marihuana predisposes the individual to use marihuana, and having marihuana-using friends provides the social opportunity for the curious. Ile individual who is already part of a, social group which uses marihuana indicates by this choice that his attitudes and values are already to some degree compatible with illicit drug use.

Social peer groups are especially influential upon individuals who have not yet become "successful" adults, such as adolescents, college students and young adults, who spend a great deal of time and effort competing for status in situations where status opportunities are minimal. The social peer group provides an opportunity for achieving status among equals by demonstrating competence and autonomy. Outstanding performance in athletics, organizations or academics demonstrates competence but not autonomy because these activities are adult-oriented and controlled. Additionally, only a relative few are able to excel.

Opportunity to prove oneself is more readily available in the peer group. Often, adolescents participate in forms of delinquent behavior, termed symbolic infractions, in order to demonstrate autonomy and competence to their peers. These include joy-riding, vandalism, sexual promiscuity, underage drinking, violation of rules of decorum and dress, and purposeless confrontation with authority.

Marihuana use has recently been added to the list of infractions and offers several advantages for adolescents and young adults. Most important, it provides a shared group experience which offers the, shy, lonely, socially awkward neophyte a means of entrance to the group, complete with its own ceremonial initiation. Repetition of the behavior serves to increase closeness and commitment to the group. Usually the experience is pleasurable and the individual is able to control his level of intoxication. This delinquency is viewed as relatively harmless to oneself and others, although its symbolic impact on parents and authority is often greater than that of other common infractions.

Therefore, a, subtle process of acquiring attitudes favorable to drug use, of having friends and acquaintances who define the marihuana experience in acceptable and pleasurable terms, and of having a social belief system which prepares one to accept the conversion process to begin with, are all powerful complementary factors which direct a young person toward marihuana use. At this point, the use of marihuana provides further opportunities for acquiring new marihuana using friends and entering the social milieu of marihuana, users.

The Dynamics of Persistent Use

The cultural and social factors sketched above, in combination with the individual's somatic and psychic characteristics, determine the pattern of his drug behavior once he has chosen to experiment with it. The majority of individuals who reach this point progress no further and often discontinue marihuana use. The most common explanation for discontinuing use is loss of interest; the effect lost its novelty and became boring. Other less common reasons are fear of legal hazards, social pressure, and concerns over physical and mental drug effects. Among the infrequently noted reasons are: interference with other activities; replacement by alcohol; unavailability; cost; unpleasant experiences; fear of moral transgression; or progression to other forms of non-drug interests such as yoga, transcendental meditation, agrarian communes, esoteric religion and restrictive diets.

For those who continue use, psychosocial factors are important determinants of the use patterns. Many marihuana users are strongly committed to traditional society in which they desire to rise socially. They have chosen to participate fully in the traditional adult-oriented activities and the formal achievement-reward system. Their peer groups consist primarily of similarly oriented individuals. The infrequent use of marihuana by these persons is a social activity for fun and satisfies curiosity.

Those individuals who continue to use marihuana more frequently appear to be different types of people and oriented toward a different part of the social system. Most of them maintain stable career orientations and continue to function within the broader society. But they feel more burdened by the traditional system of social controls and more removed from contemporary society's institutions. These individuals tend to turn away from more traditional adult-oriented reward systems and intensify their peer-group orientation. Their interests and activities emphasize an informal "in-crowd," out-of-school or work orientation. The meaning of marihuana use by this peer group emphasizes the ideological character of usage. In contrast to the infrequent type of user, these individuals seem to build their self-identity around the marihuana-using peer group.


The more one smokes marihuana, the more involved his interpersonal relationships are likely to become with his peers who share the experience with him. As he spends more time with this group, he begins to sever his contacts with conventional individuals and conventional routines. He may eventually view himself as a drug user and be willing to experiment with other drugs which are approved by his peer group. Only ;a small portion of the marihuana users who reach this stage are likely to become persistent, frequent users of these other drugs. The majority appear to experiment only.

Epidemiologic Studies

The Commission's studies have confirmed the association between marihuana usage and the consumption of other drugs for curiosity and pleasure. This association holds for all drugs, including over-thecounter and prescription pain relievers, tension relievers, sleeping pills, and stimulants as well as hashish, methamphetamines, cocaine, LSD and mescaline, and heroin. The National Survey showed that current marihuana users are about twice as likely to have used any illicit drugs than are those who have ceased using marihuana (Table 3).


Have used Currently

but no using

Substance Never used marihuana longer use marihuana

marihuana (percent)


Hashish Less than 0.5 percent 28 63

LSD or mescaline Less than 0.5 percent 11 28

Methamphetamine Less than 0.5 percent 10 23

Cocaine Less than 0.5 percent 4 10

Heroin Less than 0.5 percent 1 4

The Commission additionally has contracted a study of 105 selected, middle class, young, working adults from California, who are marihuana smokers. Of this sample, 11% were daily marihuana users and 47% used it several times a week; 33% used it several times a month; 6% used it once to several times a year; and 3% had used it but were not currently using marihuana. The study indicates that while most of the subjects were frequent marihuana users, the incidence of other drug use was relatively low (Table 4).


Percent who use marihuana


Substance who Once to Several Several

never several times times Daily

used times a month a week

marihuana a year

Hashish 42 31 21 5 0
LSD 96 4 0 0 0
Mescaline 79 19 0 0 2
Psilocybin 96 4 0 0 0
STP, DMT 100 0 0 0 0
Heroin 98 2 0 0 0
Codeine 87 11 0 0 2
Amphetamines 89 7 0 4 0
Barbiturates 86 10 4 0 0
Cocaine 75 19 2 4 0
Glue 100 0 0 0 0

With the exception of marihuana and hashish, no drug was used by more than 25% of this population and this use was almost exclusively experimental. Interestingly, the more exotic drugs, mescaline and cocaine were more frequently used (21% and 25% of this sample respectively) than the common dangerous drugs: LSD (4%), heroin (2%), codeine (11%), barbiturates (14%), and amphetamines (11%).

Among high school students, marihuana, is normally the, first illicit drug used, although several recent studies have suggested that a significant number of students initiate illicit use, with other drugs. Of the marihuana users, a majority have used no other illicit drug, and they tend to be experimental or intermittent users of marihuana.

The more frequently the adolescent uses marihuana, the more likely he is to experiment with other drugs. For example, in one recent study of San Diego high school students of predominantly white middle socioeconomic background, 80% of the students who used marihuana weekly or more often had used other drugs, and 50% of this group had used LSD. In contrast, 33% of the less than weekly users bad used other drugs.

Profiles and Dynamics

The personality profile of the heavy marihuana user discussed earlier includes elements propelling him toward heavy involvement in the multiple-drug-using-subculture. Heavy drug use by these individuals may reflect and aggravate a total alienation and disaffiliation from American society and its institutions. This group hopes to find in drug use more than simple, fun or relief from boredom. The heavy use of drugs represents a shift into the drug subculture and an adoption of a totally new life style. Some observers feel that this shift provides a new identity which allows the individual to counteract his apathy and search for meaning in a society he views as unloving, lonely, and meaningless. He seeks to become involved with what he describes as the exciting, relevant, "real" experience of life. Additionally, he believes drug use provides new feelings and awareness needed to overcome barriers between himself, others, and the natural world.

The drug culture as a community also helps to meet the needs of the individual. It provides a ready supply of drugs, unites common experiences and secrets that enhance the drug experience, and protects the individual against undesired experiences and against "the outside world." Most important, the culture instills self-confidence by reassuring the individual that he has been wise in choosing this new identity.

Frequently, these are individuals who express feelings of loneliness, isolation and over-protection from their home and family. One frequent pattern involves an intimate, dominating mother and a distant, unemotional father. In some cases, the drug-use ritual and the, sense of community closeness offered by the drug subculture appear to satisfy certain personal needs. Additionally, joining the subculture provides a release from sheltered life, a test of competence, an opportunity to participate, and a chance to express anger. When the anger is turned inward instead of directed at society and family, drug use becomes a form of passive, self-destructiveness.

Sociocultural Factors

After the individual views himself as a drug user and has become immersed in the drug-using subculture, the drugs he chooses to experiment with and his pattern of use are determined primarily by non-drug factors well beyond the simple properties of the psychoactive chemical. These factors are predominantly socioeconomic and sociocultural, although psychic and somatic factors also play a role in determining who will continue and how intensively.

The availability of a distribution system which stocks the other drugs is essential. Most often, contact with this distribution system is increased by having friends or acquaintances who use or sell other drugs. However, much of the marihuana selling takes place, at the customer level between friends, and involves little profit and relatively small quantities of the drug. The marihuana user who only buys has little contact with the professional multidrug dealing system. However, the user-buyer-seller of marihuana is more involved with the multidrug system, uses more himself and has more friends who use and sell other drugs. This factor of being a seller rather than only a buyer-user is influential in determining the degree of an individual's involvement with and commitment to the use of other drugs.

Marihuana use does not itself determine which drugs the heavily involved user will choose to use. Generally, the selection of other drugs is influenced by the social group. For example, blacks and whites have roughly equal rates of trying and using marihuana, but their choice of other drugs and the styles of drug use are quite different and distinctive, due to their frequently different sociocultural backgrounds. Additionally, one recent study of white high school and college students revealed different patterns of further drug use among males and females. Men and women used marihuana in equal numbers, but the men who used other drugs tended to use hallucinogens while the women tended to use amphetamines.

An extensive survey of drug use among 3,500 liberal arts undergraduates attending 14 campuses in the New York area demonstrated the racial character of drug use among this population (Table 5).


Meth- Amphet- Hallu-

Percentage tried drugs Heroin Cocaine amphet- amine cinogens


Blacks................ 9 16 5 9 13

Whites................ 4 7 11 19 21

According to recent studies, heroin usage is not common among white marihuana users. Heroin is most strongly linked to marihuana use in black and Spanish-speaking ghettos where many feel they have little chance of personal advancement and self-fulfillment. In such communities, a segment of the population constructs new illegitimate but accessible avenues for social coping. For some this involves the hustle (non-violent stealing) and the excitement of obtaining and using heroin and cocaine. They regard marihuana as a "cool" drug and use it for its social and calming effects.

In contrast, studies have demonstrated that the psychedelics are more often used by the white, middle to upper middle class, collegeeducated populations. The typical use of these drugs in high school college and working populations is episodic and experimental, and is usually discontinued rather rapidly in contrast with marihuana use, which for many persons is of long duration. In many instances, psychedelic drug use begins almost simultaneously with marihuana.

For a few, drug use becomes an ideologic focus, reflecting disillusionment with society and rejection of the "establishment." These and other motives, including mere pleasure-seeking, lead to continued use of LSD and other hallucinogens. Marihuana is viewed as a dilute LSD and is often used to enhance or prolong the effects of that drug. Sometimes it is encountered after first LSD use.

Methamphetamine, or "speed," use is more characteristic of those lower socioeconomic white, youth who are not school or work oriented. Living for the moment is the characteristic attitude of the speed scene. The speed user views marihuana as he does alcohol and uses it for fun or for its calming effects.

For these three groups of illicit drug users, marihuana use has different meanings and is secondary in importance to the use of the other drugs. Whether or not marihuana leads to other drug use depends on the individual, on the social and cultural setting in which the drug use takes places, and on the nature of the drug market. Its use, however, is neither inevitable nor necessary.

The Effects of Marihuana on the User

The previous section has attempted to paint a broad picture of the marihuana user. This section will deal with the, drug and its effects on these individuals.

The meaning of drug often varies with the context in which it is used. The physician would define a drug as any substance used as a medicine in the treatment of physical or mental disease. Today, due to the influence of many factors, the layman may focus on the negative connotations of drugs, such as the stupefying, poisoning, habit-forming misuse of the opiate drugs. The considerably wider and more scientific definition of a drug which will be used in this section is: any chemical substance which has an action on living tissues.

A psychoactive drug is any substance capable of modifying mental performance and individual behavior by inducing functional or pathological changes in the central nervous system.

As defined, psychoactive drugs exert their major effect on the state of the mind including emotions, feelings, sensibility, consciousness and thinking. The definition implies neither positive nor negative meanings. Chemical substances are not inherently good or bad. All substances, including medicines and foods, which man has chosen to consume have certain desired effects (whether therapeutically beneficial or pleasurable) and undesired effects (whether detrimental or unpleasant). For example, eating food is certainly a necessary and pleasurable activity. However, obesity plays an important role in many diseases, including diabetes, high blood pressure and heart attacks, and tends to limit physical activities.

The classification of any drug effect as either beneficial or harmful often greatly depends on the values the classifier places on the expected effects. This is especially relevant with respect to the psychoactive drugs such as tranquilizers, stimulants, coffee, cigarettes, alcohol, marihuana and other licit or illicit drugs. For all of these drugs, the weights of benefit and harm are difficult to determine when viewed merely in terms of their stated effects.


Marihuana refers to a preparation derived from a plant, cannabis sativa L. The preparation contains varying quantities of the flowers and their resinous secretions, leaves, small stems and seeds. These plant parts contain many chemical substances. The chemical substance which produces the major drug effects is tetrahydrocannabinol (THC). According to current information, the amount of THC present determines the potency of the preparation. Hereinafter, any reference to drug content or drug effect of marihuana will, for all practical purposes, mean that of tetrahydrocannabinol.

The drug content of the plant parts is variable, generally decreasing in the following sequence: resin, flowers, leaves. Practically no drug is found in the stems, roots or seeds. The potency and resulting drug effect of marihuana fluctuates, depending on the relative proportions of these plant parts in the marihuana mixture.

Most marihuana available in this country comes from Mexico and has a THC content of less than 1%. Marihuana of American origin often contains less than two-tenths of 1% THC. Marihuana originating in Jamaica and Southeast Asia often has a 2% to 4% THC content.

Marihuana is the least potent preparation of the plant. Jamaican ganja, containing primarily the flower tops and the small leaves or bracts, has a THC content of about 4% to 8% depending on the mixture. Indian ganja is less potent. The most potent preparation is hashish (charas) which is composed of only the drug-rich resinous secretions of the flowers. Generally, the THC content of hashish is 5 % to 12 %.


A number of variable factors exert an important influence on the psychopharmacologic effects of marihuana in man, as is true for all drugs. Failure to take these factors into consideration probably accounts for a large part of the inconsistency and controversy surrounding the description of the drug effect.


The dosage or quantity of the drug (tetrahydrocannabinol) consumed is the most important variable. As with most drugs, the larger the dose taken, the greater the physical and mental effect will be and the longer the effect will last. The effect of a high dose of marihuana on an individual would be quite different from the effect of a low, usual "social" dose.

Method of Use

The method of use has a bearing upon the drug effect. The method is directly related to both dosage and time lapse before the drug effect is felt. Injection directly into a vein delivers the total dose immediately, producing a rapid, maximal response of minimal duration. Smoking and inhalation cause rapid but less efficient delivery of the dose; variable quantity of the drug is destroyed during burning or escapes into the air and does not reach the lungs. Oral ingestion produces different effects, according to the system in which the drug is dispersed. Generally, oral ingestion diminishes the drug effect, but prolongs it.


Another factor which influences the effect of the drug is metabolism. During the metabolic process, the body cells, principally in the liver and lungs, chemically alter drug substances, changing their activity and providing for their elimination from the body. Increasing evidence indicates that marihuana is first changed by the body in a way that activates or enhances the drug effect and is subsequently altered in a way that inactivates the drug prior to its removal from the body.

The rate and direction of these metabolic steps can significantly influence the effect of marihuana. For instance, individuals with extensive exposure to marihuana or other drugs metabolize more rapidly, and perhaps differently, from those individuals with no drug exposure.

Set and Setting

An important variable in discussing the effect of marihuana on the user is the social and emotional environment; that is, the individual's "set" and "setting."

"Set" refers to a combination of factors that create the "internal environment" of the individual, including personality, life style, and philosophy, past drug experiences, personal expectations of drug effect, and mood at the time of the drug experience.

"Setting" refers to the external environment and social context in which the individual takes the drug. These factors are most influential when drugs are taken at low dosages and, like marihuana, produce minimal physical and subtle subjective mental effects. The effect of marihuana generally will be quite different for an intermittent social adult smoker from that of a youth deeply involved in the youthful drug subculture. These factors partially account for the belief of a marihuana user that he is experiencing a "high" in certain experiments even when he is given a non-marihuana substance (placebo) but is told it is marihuana.


Another important factor that determines the immediate effect of any drug is tolerance. Tolerance has two different connotations. The first, initial tolerance, is a measure of the amount of a drug which a subject must receive on first exposure to produce a designated degree of effect. A variety of innate and environmental factors contributes to initial tolerance among individuals. Different individuals require varying amounts of the drug to attain the same physical and mental effect.

The second connotation, which shall be referred to when we use the word tolerance, is that of an acquired change in tolerance. That is, within the same individual, as a result of repeated exposure to the drug, the same dose of the drug may produce a diminishing effect so that an increased amount of the drug is required to produce the same specified degree of effect.

Tolerance develops at differential rates to given effects of the same drug. If tolerance has developed to one specific effect, it has not necessarily developed to other specific effects.

By definition, the development of tolerance is neither beneficial nor detrimental. If tolerance develops rapidly to the desired mental effect of a "high" but slowly to the behavioral or physical effects, rapid increase in dose would be necessary in order to have the desired effect, and progressive behavioral and physical disruption would be seen. This is the pattern for amphetamines.

However, if tolerance develops slowly or not at all to the desired mental effects but more rapidly to the behaviorally or physically disruptive effects, no dosage increase or only a slight one would be necessary and the unpleasant and undesired effects would progressively diminish.

With regard to marihuana, present indications are that tolerance does develop to the behaviorally and physically disruptive effects, in both animals and man, especially at high frequent doses for prolonged time periods. Studies in foreign countries indicate that very heavy prolonged use of very large quantities of hashish leads to the development of tolerance to the mental effects, requiring an increase in intake to reach the original level of satisfaction. However, for the intermittent use pattern and even the moderate use pattern, little evidence exists to indicate the development of tolerance to the desired "high," although the high may persist for a shorter time period. During the Boston free-access study, no change was apparent in the level of the high produced by a relatively large dose of the drug over a 21-day period of moderate to heavy smoking.

The fact that some individuals smoke more of the drug than others may merely reflect a desire for a different level of "high." There is a tendency to develop a tolerance to the physical effects and behaviorally disruptive effects, especially the depressant effects, in heavy daily users. The development of such behavioral tolerance of this nature may explain the fact that experienced marihuana smokers describe a lower occurrence rate of undesirable drug effects. The development of tolerance may also explain why these smokers exhibit normal behavior and competent performance of ordinary tasks, while not appearing intoxicated to others even though they are at their usual level of intoxication.

Reverse Tolerance

Repeated exposure to marihuana has been said to cause an individual to need lesser amounts of the drug to achieve the same degree of intoxication. This "reverse tolerance" may be related to one's learning to get high or to the recognition of the subtle intoxication at low doses. Or perhaps, such tolerance reflects an increase in the body's ability to change the drug to an active chemical. To date, the existence of "reverse tolerance" has not been substantiated in an experimental setting.

Duration of Use

Tolerance development is only one of a variety of occurrences which possibly are related to repetitive use of marihuana. Any discussion of drug effect must also take into account the time period over which the drug use occurs. Immediate effects of a single drug experience must be contrasted with effects of short-term use and the effects of longterm use in order to detect any cumulative effects or more subtle, gradually occurring changes.

This issue of an individual's change over a period of years is quite complex; a multitude of factors other than marihuana use may affect his life. As previously defined, short-term refers to periods of less than two years, long-term to periods of two to 10 years, and very long-term to periods greater than 10 years. Most of the American experience involves short-term and long-term use, with low doses of weak preparations of the drug.

Patterns of Use

The drug effect of marihuana can be realistically discussed only within the context of who the user is, how long he has used marihuana, how much and how frequently he uses it, and the, social setting of his use.

In general, for virtually any drug, the heavier the pattern of use, the greater the risk of either direct or indirect damage. For purposes of this discussion, the patterns of use developed in the first section of this chapter will be utilized. Because frequency of use is presently the, primary determinant of use patterns in this country, we employ similar designations:

(1) The experimenter who uses marihuana, at most a few times over a short term and then generally ceases to use it, or uses once a month or less;

(2) The intermittent user who uses marihuana, infrequently, that is more than once monthly but less than several times a week;

(3) The moderate user who uses it from several times a week to once daily, generally over a long term;

(4) The heavy user who uses it several times a day over a long term and;

(5) The very heavy user who is constantly intoxicated with high tetrahydrocannabinol content preparations, usually hashish, over a very long term.

Again, these classifications are not intended to be rigid but are designed to facilitate a discussion of the many usage patterns.

Definition of Dependence

Before describing the effect of marihuana, on the user, two additional definitions are required. They concern the concept of dependence which has so clouded public and professional consideration of psychoactive drugs. Throughout the remainder of this report, we refer Separately to psychological and physical dependence, defined as follows:

Psychological dependence is the repeated use of psychoactive drugs leading to a conditioned pattern of drug-seeking behavior. The intensity of dependence varies with the nature of the drug, the method, frequency, and duration of administration, the mental and physical attributes of the individual, and the characteristics of the physical and social environment. Its intensity is at its peak when drug-seeking becomes a compulsive and undeviating pattern of behavior.

Physical dependence is the state of latent hyper-excitability which develops in the central nervous system of higher mammals following frequent and prolonged administration of the morphine-like analgesics, alcohol, barbiturates, and other depressants. Such dependence is not manifest subjectively or objectively during drug administration. Specific symptoms and signs, the abstinence syndrome, occur upon abrupt termination of drug administration; or with morphinelike agonists by administering the specific antagonists.


Set out below is a brief summary of effects of marihuana, related to frequency and duration of use. The remainder of the Chapter discusses the effects of immediate, short-term, long-term and very long-term use of the drug.

Experimenters and

intermittent users ------ Little or no psychological dependence.

Influence on behavior related largely to

conditioning to drug use and its social

value to the user.

No organ injury demonstrable.

Moderate users ------------ Moderate psychological dependence in-

creasing with duration of use.

Behavioral effects minimal in stable per-

sonalities, greater in those with emo-

tional instability.

Probably little if any organ injury.

Duration of use increases probability of

escalation of all effects including shift

from moderate to heavy use.

Heavy users -------------- American "pot head."

Strong psychological dependence.

Detectable behavior changes.

Possible organ injury (chronic diminution of pulmonary function).

Effects more easily demonstrable with long-term use.

Very heavy users ---------- Users in countries where the use of cannabis has been indigenous for centuries.

Very strong psychological dependence to point of compulsive drug seeking and use.

Clear-cut behavioral changes.

Greater incidence of associated organ injury.


The immediate effects are those which occur during the drug intoxication or shortly following it. The user is aware of some of these effects, for they often cause him to use the drug. At the same time, many changes may occur in his body which can be measured by others but are not obvious to him.

Subjective Effects

A description of an individual's feelings and state of consciousness as affected by low doses of marihuana is difficult; the condition is not similar to usual waking states and is the result of a highly individual experience. Perhaps the closest analogies are the experience of day dreaming or the moments just prior to falling asleep. The effect is not constant and a cyclical waxing and waning of the intensity of the intoxication occurs periodically.

At low, usual "social" doses, the intoxicated individual may experience an increased sense of well-being; initial restlessness and hilarity followed by a dreamy, carefree state of relaxation; alteration of sensory perceptions including expansion of space and time; and a more vivid sense of touch, sight, smell, taste, and sound; a feeling of hunger, especially a craving for sweets; and subtle changes in thought formation and expression. To an unknowing observer, an individual in this state of consciousness would not appear noticeably different from his normal state.

At higher, moderate doses, these same reactions are intensified but the changes in the individual would still be scarcely noticeable to an observer. The individual may experience rapidly changing emotions, changing sensory imagery, dulling of attention, more altered thought formation and expression such as fragmented thought, flight of ideas, impaired immediate memory, disturbed associations, altered sense of self-identity and, to some, a perceived feeling of enhanced insight.

At very high doses, psychotomimetic phenomena may be experienced. These, include distortions of body image, loss of personal identity, sensory and mental illusions, fantasies and hallucinations.

Nearly all persons who continue to use marihuana describe these usual effects in largely pleasurable terms. However, others might call some of these same effects unpleasant or undesirable.

As discussed earlier, a wide range of extra-drug factors also influences marihuana's effects. The more the individual uses marihuana and the longer he has been using it, the more likely the experiences will be predominantly pleasurable, and the less likely the effects will be unpleasant. An increasing sensitization to those effects viewed as pleasant occurs as the user has more experience with the drug.

Persons subject to unpleasant reactions may eliminate themselves from the using group although the occasional experience of an unpleasant effect does not always discourage use.

Body Function

A large amount of research has been performed in man and animals regarding the immediate effect of marihuana on bodily processes. No conclusive evidence exists of any physical damage, disturbances of bodily processes or proven human fatalities attributable solely to even very high doses of marihuana. Recently, animal studies demonstrated a relatively large margin of safety between the psychoactive dose and the physical and behavioral toxic and lethal dose. Such studies seemed to indicate that safe human study could be undertaken over a wide dose range.

Low to moderate doses of the drug produce minimal measurable transient changes in body functions. Generally, pulse rate increases, recumbent blood pressure increases slightly, and upright blood pressure decreases. The eyes redden, tear secretion is decreased, the pupils become slightly smaller, the fluid pressure within the eye lessens and one study reports that the eyeball rapidly oscillates (nystagmus).

A minimal decrement in maximum muscle strength, the presence of a fine hand tremor, and a decrease in hand and body steadiness have also been noted. Decreased sensitivity to pain and overestimation of elapsed time may occur.

The effects of marihuana on brain waves are still unclear and inconsistent. Generally, the intoxication produces minimal, transient changes of rapid onset and short duration. Sleep time appears to increase, as does dreaming.

Investigation of the effects of marihuana on a wide variety of other bodily function indices has revealed few consistently observed changes.

These few consistently observed transient effects on bodily function seem to suggest that marihuana is a rather unexciting compound of negligible immediate toxicity at the doses usually consumed in this country. The substance is predominantly a psychoactive drug. The feelings and state of consciousness described by the intoxicated seem to be far more interesting than the objective state noted by an observer.

Mental Function

Marihuana, like other psychoactive substances, predominantly affects mental processes and responses (cognitive tasks) and thus the motor responses directed by mental processes (psychomotor tasks). Generally, the degree of impairment of cognitive and psychomotor performance is dose-related, with minimal effect at low doses. The impairment varies during the period of intoxication, with the maximal effect at the peak intoxication. Performance of simple or familiar tasks is at most minimally impaired, while poor performance is demonstrated on complex, unfamiliar tasks. Experienced marihuana users commonly demonstrate significantly less decrement in performance than drug-naive, individuals.

The greater his past marihuana experience, the better the intoxicated individual is able to compensate for drug effect on ordinary performance at usual doses. Furthermore, marked individual variation in performance is noted when all else is held constant. The effect of marihuana on cognitive and psychomotor performance is therefore highly individualized and not easily predictable. Effects on emotional reactions and on volition are equally variable and are difficult to measure under laboratory conditions, but can be significant.

The Intoxicated State

Studies of intoxicated persons have suggested possible explanations for the subtle effects on mental processes produced by marihuana, Generally, a temporary episodic impairment of short-term memory occurs. These memory voids may be filled with thoughts and perceptions extraneous to organized -mental processes. Past and future may become obscured -as the individual focuses on filling the present momentary memory lapse. His sense of self -identity may seem altered if he cannot place himself in his usual time frame.

This altered state of mind may be regarded by the individual as pleasant or unpleasant. The important factors of dosage and set and setting play a most important role in this determination. When the nature of the drug-taking situation and the characteristics of the individual are optimal. the user is apt to describe his experience as one of relaxation, sensitivity, friendliness, carefreeness, thoughtfulness, happiness, peacefulness, and fun. For most marihuana users who continue to use the drug, the experience is overwhelmingly pleasurable.

Unpleasant Reactions

However, when these circumstances are not optimal, the experience may be unpleasant and an undesirable reaction to the marihuana intoxication occurs. In these instances, anxiety, depression, fatigue or cognitive loss are experienced as a generalized feeling of ill-being and discomfort. A heavy sluggish feeling, mentally and physically, is common in inexperienced marihuana smokers who overshoot the desired high or in persons who might orally ingest too large a dose. Dizziness, nausea, incoordination, and palpitations often accompany the "too stoned" feeling.

Anxiety States

"Novice anxiety reactions" or feelings of panic account for a majority of unpleasant reactions to marihuana. When the distortion of self image and time is recognized by the individual as drug-induced and temporary, the experience is viewed as pleasurable. Anxiety -and panic result when these changes cause the individual to fear that the loss of his identity and self-control may not end, and that he is dying or "losing his mind." These anxiety and panic reactions are transient and usually disappear over a few hours as the drug's effects wear off, or more quickly with gentle friendly reassurance.

The large majority of these, anxiety reactions occur in individuals who are experimenting with marihuana. Most often these individuals have an intense underlying anxiety surrounding marihuana use, such as fears of arrest, disruption of family and occupational relations, and possible bodily or mental harm. Often they are older and have relatively rigid personalities with less desire for new and different experiences.

The incidence of these anxiety reactions may have decreased as marihuana use has become acceptable to wider populations, as the fears of its effects have lessened and as users have developed experience in management of these reactions.


Rare cases of full-blown psychotic episodes have been precipitated by marihuana. Generally, the individuals had previous mental disorders or had poorly developed personalities and were marginally adjusted to their life situation. Often the episode occurred at times of excessive stress. These episodes are characteristically temporary. Psychotherapy and sometimes medications are useful in prompt control and treatment of this psychological reaction. In addition, rare nonspecific toxic psychoses have occurred after extremely high doses. This state of nonspecific drug intoxication or acute brain syndrome is self-limited and clears spontaneously as the drug is eliminated from the body.


In summary, the immediate effect of marihuana on normal mental processes is a subtle alteration in state of consciousness probably related to a change in short-term memory, mood, emotion and volition. This effect on the mind produces a varying influence on cognitive and psychomotor task performance which is highly individualized, as well as related to dosage, time, complexity of the task and experience of the user. The effect on personal, social and vocational functions is difficult to predict. In most instances, the marihuana intoxication is pleasurable. In rare cases, the experience may lead to unpleasant anxiety and panic, and in a predisposed few, to psychosis.


The effect of an enormous daily oral dose of the drug (up to about one hundred thousand times the minimal behaviorally effective human dose) was recently studied in rats and monkeys for three months. A severe, generalized nervous system depression was evident the first few days. Evidence of cumulative toxicity was observed at these doses. Severe central -nervous system depression produced fatalities in some rats in the first few days until tolerance developed. Later, extreme hyperactivity developed.

The monkeys experienced severe central nervous system depression and one group showed mild hyperactivity, but all rapidly returned to normal behavior after the development of tolerance to these effects. Minimal dose-related toxic effects on bodily organs were noted at autopsy at the conclusion of the experiment. These non-specific findings of unknown meaning included bypocellularity of the bone marrow and spleen and hypertrophy of the adrenal cortex.

A 28-day study employing intravenous administration of from one to ten thousand times the minimal effective human dose to monkeys produced -similar findings clinically. In the high dose groups delayed deaths from acute hemorrhagic pneumonia were possibly caused by accumulation of clumps of THC in the lung producing irritation similar to that seen at the injection sites. No other organ pathology was noted. These animal studies illustrated that the margin of safety between active dose and toxic dose was enormous.

A few studies have recently been carried out to observe the effect of a few weeks of daily marihuana smoking in man. The amount smoked was a relatively large American dose. Frequency of use was once to several times daily.

During the 21-day Boston free-access study, no harmful effects were observed on general bodily functions, motor functions, mental functions, personal or social behavior or work performance. Total sleep time and periods of sleep were increased. Weight gain was uniformly noted.

No evidence of physical dependence or signs of withdrawal were noted. In the heaviest smokers, -moderate psychological dependence was suggested by an increased negative mood after cessation of smoking.

Tolerance appeared to develop to the immediate effects of the drug on general bodily functions (pulse rate) and psychomotor-cognitive performance (time estimation, short-term memory, and shootinggallery skill) but not to the "high." Marihuana intoxication did not significantly inhibit the ability of the subjects to improve with practice through time on these psychological-motor tasks.

Neither immediate nor short-term (21 day) high-dose marihuana intoxication decreased motivation to engage in a variety of social and goal-directed behaviors. No consistent alteration that could be related to marihuana smoking over this period of time was observed in work performance of a simple task, participation in aspects of the research study, or interest and participation in a variety of personal activities, such as writing, reading, interest and knowledge of current world events, or participation in athletic or aesthetic activities.

Marihuana smoking appeared to affect patterns of social interactions. Although use of the drug was found to be a group social activity around which conversation and other types of social behavior were centered, it was not uncommon for some or all of the smokers to withdraw from the social interaction and concentrate on the subjective drug experience.

During the first part of the smoking period, both intermittent and daily users demonstrated a marked decrement in total interaction. Total interaction continued to diminish among intermittent users but increased above presmoking levels among the daily users during the later parts of the smoking period. The quality of the interaction was more convivial and less task-oriented when marihuana was available to the group.

Additionally, an assessment of the effect of marihuana on risktaking behavior revealed that daily users tended to become more conservative when engaging in decision-making under conditions of risk.


Our knowledge about marihuana is incomplete, but certain behavior characteristics appear to be emerging in regard to long term American marihuana use which, for the most part, is significantly less than 10 years. These impressions were confirmed in the Boston free-access study. The group of American young adults studied averaged five years (range 2-17 years) of intermittent or daily use, of marihuana.

No significant physical, biochemical, or mental abnormalities could be attributed solely to their marihuana smoking. Some abnormality of pulmonary function was demonstrated in many of the subjects which could not be correlated-with quantity, frequency or duration of smoking marihuana and/or tobacco cigarettes. (One other investigation recently completed uncovered no abnormalities in lung or heart functioning of a group of non-cigarette smoking heavy marihuana users). Many of the subjects were in fair to poor physical condition, as judged by exercise tolerance.

The performance of one-fifth of the subjects on a battery of tests sensitive to brain function was poorer on at least one, index than would have been predicted on the basis of their IQ scores and education. But a definite relationship between the poor test scores and prior marihuana or hallucinogen use could not be proven.

In the past few years, observers have noted various social, psychological and behavioral changes among young high school and college age Americans including many who have used marihuana heavily for a number of years. These changes are reflected by a loss of volitional goal direction. These individuals drop out and relinquish traditional adult roles and values. They become present rather than future oriented, appear alienated from broadly accepted social and occupational activity, and experience reduced concern for personal hygiene and nutrition.

Several psychiatrists believe they have detected clinically that some heavy marihuana-using individuals appear to undergo subtle changes in personality and modes of thinking, with a resulting change in life style. In adopting this new life style, a troubled youth may turn toward a subculture where drug use and untraditional behavior are acceptable.

This youthful population resembles in many respects the marihuana smoker described in the Boston study. No evidence exists to date to demonstrate that marihuana use alone caused these behavioral changes either directly or indirectly. Many individuals reach the same point without prior marihuana use or only intermittent or moderate use; and many more individuals use marihuana as heavily but do not evidence these changes. For some of these young people, the drop out state is only a temporary phase, preceding a personal reorganization and return to a more conventional life style.

If heavy, long-term marihuana use is linked to the formation of this complex of social, psychological and behavioral changes in young people, then it is only one of many contributing factors.


Knowledge of the effects of very heavy, very long-term use of marihuana by man is still incomplete. The Commission has extensively reviewed the world literature as well as ongoing studies in Jamaica and Greece, and carefully observed very heavy, very long-term using populations in countries in other parts of the world, such as Afghanistan and India. These populations smoke and often drink much stronger drug preparations, hashish and ganja, than are commonly used in America. From these investigations, some observable consequences are becoming much clearer.

Tolerance and Dependence

Some tolerance does occur with prolonged heavy usage; large drug doses are necessary for the desired effects. Abrupt withdrawal does not lead to a specific or reproducible abstinence syndrome and physical dependence has not been demonstrated in man or in animals. The very heavy users studied did evidence strong psychological dependence, but were able to cease use for short periods of time. In these users,

withdrawal does induce, symptoms characteristic of psychological dependence. The anxiety, restlessness, insomnia, and other non-specific symptoms of withdrawal are very similar in kind and intensity to those experienced by compulsive cigarette smokers.

Although the distress of withdrawal exerts a very strong psychogenic drive to continue use, fear of withdrawal is, in most cases, not adequate to inspire immediate criminal acts to obtain the drug.

General Body Function

In the Jamaican study, no significant physical or mental abnormalities could be attributed to marihuana use, according to an evaluation of medical history, complete physical examination, chest x-ray, electrocardiogram, blood cell and chemistry tests, lung, liver or kidney function tests, selected hormone evaluation, brain waves, psychiatric evaluation, and psychological testing. There was no evidence to indicate that the drug as commonly used was responsible for producing birth defects in offspring of users. This aspect is also being studied further.

Heavy smoking, no matter if the substance was tobacco or ganja, was shown to contribute to pulmonary functions lower than those found among persons who smoked neither substance. All the ganja smokers studied also smoked tobacco. In Jamaica, ganja is always smoked in a mixture with tobacco; and many of the subjects were heavy cigarette smokers, as well.

In a study of a Greek hashish-using population preliminary findings revealed poor dentition, enlarged livers, and chronic bronchitis. Further study is required to clarify the relationship of these to hashish use, alcohol or tobacco use, or general life style of this user population.

Social Functioning

Similarly, the Jamaican and Greek subjects did not evidence any deterioration of mental or social functioning which could be attributed solely to heavy very long-term cannabis use.

These individuals appear to have used the drug without noticeable behavioral or mental deviation from their lower socioeconomic group norms, as detected by observation in their communities and by extensive sociological interviews, psychological tests and psychiatric examination.

Overall life style was not different from non-users in their lower socioeconomic community. They were alert and realistic, with average intelligence based on their education. Most functioned normally in their communities with stable families, homes, jobs, and friends. These individuals seem to have survived heavy long-term cannabis use without major physical or behavioral defects.

Mental Functioning

The incidence of psychiatric hospitalizations for acute psychoses and of use of drugs other than alcohol is not significantly higher than among the non-using population. The existence of a specific longlasting, cannabis-related psychosis is poorly defined. If heavy cannabis use produces a, specific psychosis, it must be quite rare or else exceedingly difficult to distinguish from other acute or chronic psychoses.

Recent studies suggest that the occurrence of any form of psychosis in heavy cannabis users is no higher than in the general population. Although such use is often quite, prevalent in hospitalized mental patients, the drug could only be considered a. causal factor in a, few cases. Most of these were, short-term reactions or toxic overdoses. In addition, a concurrent use of alcohol often played a role in the, episode causing hospitalization.

These findings are somewhat surprising in view of the widespread belief that cannabis attracts the mentally unstable, vulnerable individual. Experience in the United States has not involved a level of heavy marihuana, use comparable to these foreign countries. Consequently, such long-lasting psychic disturbances possibly caused by heavy cannabis use have not been observed in this country.

Motivation and Behavioral Change

Another controversial form of social-mental deterioration allegedly related to very long-term very heavy cannabis use is the "amotivational syndrome." It supposedly affects the very heavy using population and is described world-wide as a, loss of interest in virtually all activities other than cannabis use, with resultant lethargy, amorality, instability and social and personal deterioration. The reasons for the occurrence of this syndrome are varied and hypothetical; drug use is only one of many components in the socioeconomic and psychocultural backgrounds of the individuals.

Intensive studies of the Greek and Jamaican populations of heavy long-term cannabis users appear to dispute the sole causality of cannabis in this syndrome. The heavy ganja and hashish using individuals were from lower socioeconomic groups, and possessed average intelligence but had little education and small chance of vocational advancement. Most were married and maintained families and households. They were all employed, most often as laborers or small businessmen, at a level which corresponded with their education and opportunity.

In general, their life styles were dictated by socioeconomic factors and did not appear to deteriorate as a result of cannabis use. The Jamaicans were working strenuously and regularly at generally uninteresting jobs. In their culture, cannabis serves as a work adjunct. The users believe the drug provides energy for laborious work and helps them to endure their routine tasks.

In contrast, others have described Asian and African populations where heavy to very heavy hashish or charas smoking for a very long time is associated with clear-cut behavioral changes. In these societies, the smokers are mostly jobless, illiterate persons of the lowest socioeconomic backgrounds. They generally begin to use the drug in their early teens and continue its use up to their 60's.

The users prefer to smoke in groups of two to 20, generally in a quiet place out of the reach of non-smokers. Weakness, malnutrition and sexual difficulties, usually impotence, a-re common. Some of them report sleep disturbances.

Most users who have used the drug for 20 to 30 years are lazy and less practical in most of their daily acts and reluctant to make decisions. However, their ability to perform non-complicated tasks is as good as non-smokers.

Although the smokers think they become faster in their daily work, a general slowness in all their activities is noticed by others. This user population is typically uncreative. They make little if any significant contribution to the social, medical or economic improvement of their community.


Once existing marihuana, policy was cast into the realm of public debate, partisans on both sides of the issue over-simplified the question of the effects of use of the, drug on the individual. Proponents of the prohibitory legal system contended that marihuana, was a, dangerous drug, while opponents insisted that it was a harmless drug or was less harmful than alcohol or tobacco.

Any psychoactive drug is potentially harmful to the individual, depending on the intensity, frequency and duration of use. Marihuana is no exception. Because the particular hazards of use differ for different drugs, it makes no sense, to compare the harmfulness of different drugs. One may compare, insofar as the individual is concerned, only the harmfulness of specific effects. Is heroin less harmful than alcohol because, unlike alcohol, it directly causes no physical in-jury? Or is heroin more harmful than alcohol because at normal doses its use is more incapacitating in a behavioral sense?

Assessment of the relative dangers of particular drugs is meaningful only in a wider context which weighs the possible benefits of the drugs, the comparative scope of their use, and their relative impact on society at large. We consider these questions in the next Chapter, particularly in connection with the impact on public health.

Looking only at the effects on the individual, there, is little proven danger of physical or psychological harm from the experimental or intermittent use of the natural preparations of cannabis, including the resinous mixtures commonly used in this country. The risk of harm lies instead in the heavy, long-term use of the drug, particularly of the most potent preparations.

The experimenter and the intermittent users develop little or no psychological dependence on the drug. No organ injury is demonstrable.

Some moderate users evidence a degree of psychological dependence which increases in intensity with prolonged duration of use. Behavioral effects are lesser in stable personalities but greater in those with emotional instability. Prolonged duration of use does increase the probability of some behavioral and organic consequences including the possible shift to a heavy use pattern.

The heavy user shows strong psychological dependence on marihuana and often hashish. Organ injury, especially diminuation of pulmonary function, is possible. Specific behavioral changes are detectable. All of these effects are more apparent with long-term and very long-term heavy use than with short-term heavy use.

The very heavy users, found in countries where the use of cannabis has been indigenous for centuries, have a compulsive psychological dependence on the drug, most commonly used in the form of hashish. Clear-cut behavioral changes and a greater incidence of associated biological injury occur as duration of use increases. At present, the Commission is unaware of any similar pattern in this country.

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