Study: Marijuana Not Linked With Long Term Cognitive Impairment
By Maia Szalavitz
The idea that “marijuana makes you dumb” has long been embodied in the stereotype of the slow, stupid stoner, seen in numerous Hollywood movies and TV comedies and going unquestioned by much of American culture. But a new study says no: the researchers followed nearly 2,000 young Australian adults for eight years and found that marijuana has little long-term effect on learning and memory— and any cognitive damage that does occur as a result of cannabis use is reversible.
Participants were aged 20-24 at the start of the study, which was part of a larger project on community health. Researchers categorized them as light, heavy, former or non-users of cannabis based on their answers to questions about marijuana habits.
Light use was defined as smoking monthly or less frequently; heavy use was weekly or more often. Former users had to have not smoked for at least a year. Fully 72% of the participants were non-users or former users; 18% were light users and 9% were heavy current users. Prior studies have found that drug users do accurately report their consumption levels in surveys like this as long as anonymity is guaranteed and there are no negative consequences for telling the truth.