It is very likely that anyone who has heard the term “marijuana” has also heard of its supposed negative effects on brain development. One manner of evaluating brain development is the measurement of volume or size of various individual regions. The authors of this study set out to evaluate the reputed impact of cannabis (marijuana) on brain morphology (development).
Two large population-based twin samples from the United States and Australia were used. A total of 622 young Australian adults and 474 middle-aged US males of predominantly Anglo-Saxon ancestry participated, and complete substance use and imaging data was gathered.
They used MRI and volumetric segmentation to estimate volume in 7 distinct regions of interest in the brains of all participants. The authors concluded that cannabis use is statistically unrelated to individual differences in brain morphology as measured by subcortical volume.
