Why Weed Won’t Destroy Your Brain

April 17, 2014 | Andy Cush

A new study published in the Journal of Neuroscience that’s been making the rounds lately purports that smoking weed, even casually, damages your brain in serious ways. Researchers at Northwestern University studied 40 people, half of whom smoked pot and half of whom didn’t, and the smokers brains exhibited abnormalities not present in the non-smokers’. In conclusion, lead author Hans Breiter told USA Today, “just casual use appears to create changes in the brain in areas you don’t want to change.” Panic!

Except, as Maia Szalavitz points out at The Daily Beast“different” doesn’t necessarily mean “worse.” The team did no behavioral studies to determine how, if at all, the abnormalities manifest themselves so their supposed proof lies entirely in brain scan results. Furthermore, people who exhibited any cannabis-related problems were barred from participating in the study from the outset, meaning all of the researchers’ subjects were healthy. Salavitz writes:

Although the pot-smoking participants showed brain differences in comparison to the controls who were also selected to be normal— both groups were normal! If the smokers had any marijuana-related problems or any type of impairment, they would not have been included in the first place. Therefore, the brain changes that the researchers found were—by definition—not associated with any cognitive, emotional, or mental problems or differences.

“I’m disappointed that scientists are still able to publish high profile papers that only look at neuroimaging without a behavioral endpoint,” Carl Hart, a psychology professor at Columbia, told Salavitz. Though there are identifiable structural differences between the brains of men and women, he added by way of example, “we don’t say this means women are impaired.”

So yes, while smoking weed might alter the shape of your brain — though even the group’s conclusions about causation are sketchy, as Salavitz shows — this study does nothing to prove it will make you any dumber or less motivated.

(Photo: @Blind Nomad)