Use of marijuana and other drugs among adult marijuana users: A longitudinal study

The drug use of 97 adult regular marijuana-user volunteers who were interviewed in 1970 and were re-interviewed in 1976 is presented. At the original interview the majority were using marijuana one to four times per week. By follow-up, most had either decreased to only occasional use or had increased to near daily use. Use of cigarettes, hallucinogens, stimulants, barbiturates, and opiates had declined. Alcohol was being more frequently used at follow-up. Use of nearly all substances reported at the original interview was correlated with the use reported at follow-up. Five global levels of drug use were examined, from those using very little alcohol and no cigarettes (level 1) to marijuana use (level 3) to use of substances from among four categories of “harder” drugs (level 5). The majority of persons had moved to a lower level by follow-up, with only 10% moving to a higher level. Marijuana-use frequency was related to extent of other drug use at the original but not at the follow-up interview. Cessation of harder drug use was found to be best predicted by marriage, and by having friends who were not marijuana users.