The size and shape of two brain regions involved in emotion and motivation may differ in young adults who smoke marijuana at least once a week, according to a new study published April 16 in The Journal of Neuroscience.
The findings suggest that recreational marijuana use may lead to brain changes even if its lightly or moderately used.
Previous studies exposing animals to tetrahydrocannabinol (THC) — the main psychoactive component of marijuana — show that repeated exposure to the drug causes structural changes in brain regions involved with these functions. However, less is known about how low to moderate marijuana use affects brain structure in people, particularly in teens and young adults.
In the current study, Jodi Gilman, PhD, Anne Blood, PhD, and Hans Breiter, MD, of Northwestern University and Massachusetts General Hospital/Harvard Medical School used magnetic resonance imaging (MRI) to compare the brains of 18- to 25-year olds who reported smoking marijuana at least once per week with those with little to no history of marijuana use. Imaging data revealed they had significant brain differences. The nucleus accumbens — a brain region known to be involved in reward processing — was larger and altered in its shape and structure in the marijuana users compared to non-users.
“This study suggests that even light to moderate recreational marijuana use can cause changes in brain anatomy,” said Carl Lupica, PhD commented to Science Daily. “These observations are particularly interesting because previous studies have focused primarily on the brains of heavy marijuana smokers, and have largely ignored the brains of casual users.”
JOURNAL SOURCE: Society for Neuroscience (SfN). (2014, April 15). Brain changes associated with casual marijuana use in young adults, study finds. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2014/04/140415181156.htm