Boulder, CO: Marijuana use is not associated with structural changes in the brain, according to imaging data published in The Journal of Neuroscience.
Investigators from the University of Colorado at Boulder and the University of Louisville in Kentucky assessed brain morphology in both daily adult and adolescent cannabis users compared to non-users, with a particular focus on whether any differences were identifiable in the nucleus accumbens, amygdala, hippocampus, and the cerebellum.
Investigators reported "no statistically significant differences ... between daily users and nonusers on volume or shape in the regions of interest" after researchers controlled for participants' use of alcohol.
"[T]he 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," researchers reported.
The study's results failed to replicate well-publicized findings reported in the same journal in 2014 purporting to associate cannabis use by young adults with changes in brain morphology. Authors of the new study theorized that the contradictory results were likely because of previous researchers' failure to adequately control for the effects of alcohol, which "has been unequivocally associated with deleterious effects on brain morphology and cognition in both adults and adolescents."
Researchers concluded, "[I]t seems unlikely that marijuana use has the same level of long-term deleterious effects on brain morphology as other drugs like alcohol. ... The press may not cite studies that do not find sensational effects, but these studies are still extremely important."
For more information, please contact Paul Armentano, NORML Deputy Director, at: firstname.lastname@example.org. Full text of the study, "Daily marijuana use is not associated with brain morphometric measures in adolescents or adults," appears in The Journal of Neuroscience.