Wrong Stereotype: Marijuana Does Not Make You Dumb

We all know the stereotype of the "dumb stoner." Well, one study says it is not true -- marijuana does not make you stupid.

Time magazine reports that the study from Australian National University followed 2,000 young adults for eight years and found that pot had very little long-term effect on learning and memory. Also, any damage that does occur is reversible.

Participants took memory and intelligence tests three times over the eight years. They were also asked about how their marijuana use had changed. Researchers found that people who were still smoking marijuana performed worse on the tests. However, when the investigators controlled for factors like education and gender, almost all of the differences disappeared.

The authors write:

The adverse impacts of cannabis use on cognitive functions either appear to be related to pre-existing factors or are reversible in this community cohort even after potentially extended periods of use. These findings may be useful in motivating individuals to lower cannabis use, even after an extensive history of heavy intake.

There of course have been studies that show that the brains of marijuana smokers are indeed adversely affected. But many of those studies only tested smokers within a year of quitting, not years later like this study.

The research was published in the journal Addiction.