Chronic marijuana use may alter the brain

Guest post by Kate Baggaley

Long-term marijuana use may cause structural changes in the brain, researchers report November 10 in the Proceedings of the National Academy of Sciences. Among 48 users and 62 nonusers, the marijuana users’ brains had lower volume of gray matter and more connectivity in white matter, the tissue that transmits signals. Gray matter may be more vulnerable to the effects of cannabis than white matter, the researchers report.

Future studies will be needed to determine whether these effects are permanent or reversible. For more on marijuana, read SN’s feature “Legalization trend forces review of marijuana’s dangers.”