Schaffer Library of Drug Policy

Marihuana: A Signal of Misunderstanding

Marihuana Use and Its Effects - Mental Function

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

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.


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