Patterns of use and psychopathology in chronic marijuana users.

After an epidemic increase in the use of marijuana from the mid 1960s to the late 1970s, there appears to be a recent decrease in the prevalence of use. Patterns of use of marijuana vary considerably depending upon the socio-cultural and psychobiologic characteristics of the user. There may also be a natural history of marijuana use in individuals that is influenced importantly by the age and perspectives of the user. Marijuana use has been shown to be an important cause of psychopathology in some people and an attempt at self-medication in others.