A new, well-controlled study examining cannabis’ impact on adult and adolescent brains observed that even daily use did not induce structural changes. This recent data, published in The Journal of Neuroscience, is significant in that it took into consideration several variables that confounded previous research reporting abnormalities in the size and volume in some areas of cannabis users' brains. Apparently earlier science was forgetting to measure a pretty important contributing factor: alcohol use.
For this study, scientists compared MRI scans of 29 adult consumers and 29 non-users, along with 50 adolescent users and 50 non-users. The brain regions in question included the hippocampus, amygdala, nucleus accumbens, and cerebellum. These scans, in conjunction with statistical analysis, showed no differences in these brain regions between both groups.
The problem with many of these studies is their inability to differentiate correlation from causation. While this new research arrives with its own cause-and-effect limitations (e.g., the impact of socioeconomic status and history of cannabis use), it did match groups with confounding variables like age, gender, and alcohol use, thereby improving the validity of results. It's surprising that few researchers before thought to consider other types of substance abuse, particularly alcohol as it is both common and known to affect brain structure and cognition.
Only three days ago, we covered new research showing no link between cannabis and lung health decline. And then the American Academy of Pediatrics called for the Federal rescheduling of marijuana. We can only hope that better science will lead to better drug policies in the end.
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