Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana Use and Its Effects - Epidemiologic Studies

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
Previous Page Next Page

The National Commission on Marihuana and Drug Abuse

Marihuana - A Signal of Misunderstanding.

Chapter II

marihuana use and its effects

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.

Previous Page Next Page