The National Commission on Marihuana and Drug Abuse

Marihuana - A Signal of Misunderstanding.

Chapter II

marihuana use and its effects

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.