A long-running investigation into cannabis use has found a strong link between hammering it as a teenager and growing up stupid, with the IQs of more keen users dropping as a result of years of early use.
The test tracked the lives of 1,037 people from birth until the age of 38, interviewing them at the ages of 18, 21, 26, 32, and 38 to get a handle on their level of marijuana use. The survey found evidence of a fall in brain power in those who were heavy users of the drug from an early age, with the drop in IQ the most severe in those who started smoking during adolescence.
The brain testing was dome at the ages of 13 and 38, with those who were "persistent" cannabis users from a young age showing "neuropsychological decline broadly across domains of functioning" as a result of their use. Interestingly, those who started smoking as adults showed no signs of similar brain breakage.
Furthermore, stopping didn't make the brains of early starters better. The damage was done early, with the heavier users showing greater declines, thanks to what the researchers believe is "a neurotoxic effect of cannabis on the adolescent brain."
Image credit: Marijuana from Shutterstock