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. MORE: U.S. Rules That Marijuana Has No Medical Use. What Does Science Say? Participants took tests of memory and intelligence three times over the eight year period the study. They were also asked about how their marijuana use had changed. When the results were at last tabulated, researchers found that there were large initial differences between the groups, with the current marijuana smokers performing worse on tests that required them to recall lists of words after various periods of time or remember numbers in the reverse order from the one in which they were presented. However, when the investigators controlled for factors like education and gender, almost all of these differences disappeared.  The lower education levels of the pot smokers — and their greater likelihood of being male — had made it look like marijuana had significantly affected their … Continue reading Study: Marijuana Not Linked With Long Term Cognitive Impairment