22-Year Long Study Finds Marijuana Has No Effect on Physical or Mental Health

A study published in the Psychology of Addictive Behaviors journal found no long-term health effects associated with marijuana use.

Researchers at the University of Pittsburgh Medical Center and Rutgers University began the study in the late 1980s, and used then-14 year old males drawn from Pittsburgh public schools. Four groups were tracked until 2009 and 2010, when the participants were 36 years old…The study found no statistical change in physical or mental health among any of the four groups between the beginning and end of the research period. Even without controlling for other factors, chronic users did not have a worse health prognosis than individuals in the other groups.


Some evidence suggests that youth who use marijuana heavily during adolescence may be particularly prone to health problems in later adulthood (e.g., respiratory illnesses, psychotic symptoms). However, relatively few longitudinal studies have prospectively examined the long-term physical and mental health consequences associated with chronic adolescent marijuana use. The present study used data from a longitudinal sample of Black and White young men to determine whether different developmental patterns of marijuana use, assessed annually from early adolescence to the mid-20s, were associated with adverse physical (e.g., asthma, high blood pressure) and mental (e.g., psychosis, anxiety disorders) health outcomes in the mid-30s. Analyses also examined whether chronic marijuana use was more strongly associated with later health problems in Black men relative to White men. Findings from latent class growth curve analysis identified 4 distinct subgroups of marijuana users: early onset chronic users, late increasing users, adolescence-limited users, and low/nonusers. Results indicated that the 4 marijuana use trajectory groups were not significantly different in terms of their physical and mental health problems assessed in the mid-30s. The associations between marijuana group membership and later health problems did not vary significantly by race. Findings are discussed in the context of a larger body of work investigating the potential long-term health consequences of early onset chronic marijuana use, as well as the complications inherent in studying the possible link between marijuana use and health effects.

Clinical Trials, Studies and Publications:

Chronic Adolescent Marijuana Use as a Risk Factor for Physical and Mental Health Problems in Young Adult Men