New Research in Mice Provides Further Evidence that Marijuana Harms the Developing Brain

NIDA-supported researchers at the University of Maryland School of Medicine have found further evidence that marijuana exposure during adolescence, when prefrontal areas of the brain are still maturing, can produce long-lasting cognitive impairment. Adolescent mice who were exposed to low doses of cannabinoids for 20 days were found to have suppressed cortical oscillations in frontal brain areas and impaired working memory that persisted into adulthood. Adult mice exposed to the same dose for the same length of time did not show these effects. Cortical oscillations, or the rhythm of neural firing across brain areas, play a role in cognitive functions like attention, integrating sensory information, and working memory, and they are known to be reduced also in schizophrenia and other diseases. The adolescent brain’s unique sensitivity to being modified by cannabinoids has been indicated in other human and animal studies, although this is the first study to directly link adolescent exposure to abnormal electrophysiological activity in the adult brain.

For a copy of the study abstract, go to www.nature.com/npp/journal/vaop/ncurrent/abs/npp2013164a.html