Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marijuana -- Factors Influencing Psychopharmacological Effect - Duration of Use

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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Factors Influencing Psychopharmacological Effect


Very little American data exists on the duration of marihuana use. Practically no data exists which demonstrates the extent that persons who initiated marihuana use some 20-40 years ago have continued its use. Robins and Murphy (1967) in a follow-up study of St. Louis black males noted that 20% of those who had tried marihuana by age 24 were still using it to some degree 15 years later. McGlothlin et a]. (1970, 1971) reported on a sample of predominantly white adults who began using, marihuana in adolescence and had continued infrequent use for more than 20 years.

In the case of Western and particularly middle class American use of marihuana, the rapid climb to prominence of the phenomenon since the midsixties raises the question of whether the entire drug movement is transient or permanent. Certainly, the majority of the youthful users and many of the adults have used the drug less than 10 years and probably less than five years.

One 1970 survey (Lipp, 1970) revealed that 77% of those students who initiated marihuana use four to five years earlier were still using it to some degree. A recent study (Walters et a]., 1972) indicates that students who first used marihuana before entering college in September 1965 and had continued use of marihuana in February 1969 ("old user") differed from the, vast majority of users who began their drug use in college ("new user").

The old user is more likely to experiment with a wide variety of drugs, to be extremely active in radical political organizations, to be alienated from American society, to be less definite about career plans, and to have more heterosexual activities.

The Commission-sponsored National Survey indicated that marihuana use by both youth (12-17 years of age) and adults (18 and over) is experimental in approximately 75% of those who have ever used marihuana. These individuals have, either stopped using it (66% of adults and 57% of youth) or are, using, it once, a month or less. In contrast, 13% of the ever used subsample (12% adults, 16% youth) use marihuana once a week or more.

In other non-Western countries, cannabis use frequently persists for long periods. Especially in the East, persons using it for 20-40 years or more are not uncommon. In other cultures, initiation is most common in adolescence. Once the habit is established it is likely to continue on a daily basis for many years and frequently continues as a lifetime practice (Weiss, 1971; Sigg, 1963; Soueif, 1967; Watt, 1936; Chopra and Chopra, 1939; Bouquet, 1951; VN, 1957).

Probably the duration of use will vary considerably depending on cultural acceptance or rejection (McGlothlin, 1972).

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