New research published in The Journal of Neuroscience has confirmed what most pot smokers will gladly tell you: that daily consumption of marijuana is not associated to physical changes in certain regions of the brain. From the study:
Groups were matched on a critical confounding variable, alcohol use, to a far greater degree than in previously published studies. We acquired high-resolution MRI scans, and investigated group differences in gray matter using voxel-based morphometry, surface-based morphometry, and shape analysis in structures suggested to be associated with marijuana use, as follows: the nucleus accumbens, amygdala, hippocampus, and cerebellum. No statistically significant differences were found between daily users and nonusers on volume or shape in the regions of interest. Effect sizes suggest that the failure to find differences was not due to a lack of statistical power, but rather was due to the lack of even a modest effect. In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures.
At the end of the day, marijuana didn’t have some of the negative impacts that other research and media pundits claim it does. And that’s probably something that just about anyone who’s ever smoked marijuana could tell you.