Why the Media’s Fearmongering on Marijuana Effects on the Brain Is Faulty

AlterNet

The mainstream media launched into a reefer mad frenzy this week after researchers from Harvard University in Boston and Northwestern University in Chicago published the results of a neuroimaging study assessing the brains of a small cohort of regular marijuana smokers and non-users. The brain scans identified various differences between the two groups in three aspects of brain morphometry: gray matter density, volume, and shape. These differences triggered dozens of high-profile media outlets to lose their collective minds. Here’s just a sample of the screaming headlines:

CNN: Casual marijuana use may damage your brain; Science Daily: More joints equal more damage; Financial Post: Study proves 

occasional marijuana use is mind altering; Time: Recreational pot use harmful to young people’s brains; Smoking cannabis will change you. That’s not a risk, its a certainty.

Just imagine how the media would have responded if the study in question had included more than 20 actual cases — or if the authors had actually bothered to assess its subjects for demonstrable deficits in cognitive performance. Yes, that’s right. Despite the sky-is-falling rhetoric and the shock claims of permanent brain damage, a careful review of the study and its findings reveals little, if any, cause for alarm.

So what did the study find? In truth, not a whole lot.

Using high–resolution MRI imaging, scientists identified specific changes in particular regions of the brain that they inferred were likely due to marijuana exposure. (Since researchers only performed a single MRI session, they could not say definitively whether these changes were, in fact, caused by cannabis or whether they existed prior to subjects’ use of the plant.) Notably, however, these changes did not appear to be associated with any overt adverse effects in subjects’ actual cognition or behavior. (Separate studies assessing youth use of legal intoxicants, such as nicotine and alcohol,have also been associated with documented changes in brain structure. Ditto for caffeine intake in preclinical models. These findings have received far less media attention.)

Both the cases (20 marijuana users) and controls (20 nonusers) in the study were recruited from local universities, undermining the notion that the alleged ‘ brain damaged potheads’ were any more academically challenged than their non-using peers. Further, as summarized by HealthDay: “Psychiatric interviews revealed that the pot smokers did not meet criteria for drug dependence. For example, marijuana use did not interfere with their studies, work or other activities, and they had not needed to increase the amount they used to get the same high.”

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