Cannabis Use is Quantitatively Associated with Nucleus Accumbens and Amygdala Abnormalities in Young Adult Recreational Users


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Jodi M. Gilman,1,4,5 John K. Kuster,1,2* Sang Lee,1,6* Myung Joo Lee,1,6* Byoung Woo Kim,1,6 Nikos Makris,3,5 Andre van der Kouwe,4,5 Anne J. Blood,1,2,4,5† and Hans C. Breiter1,2,4,6† 1 Laboratory of Neuroimaging and Genetics, Department of Psychiatry, 2 Mood and Motor Control Laboratory, 3 Center for Morphometric Analysis, Department of Psychiatry, and 4 Athinoula A. Martinos Center in Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, 5 Harvard Medical School, Boston, Massachusetts 02115, and 6 Warren Wright Adolescent Center, Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois 06011


Marijuana is the most commonly used illicit drug inthe United States, but little is known about its effects on the human brain, particularly on reward/aversion regions implicated in addiction, such as the nucleus accumbens and amygdala. Animal studies show structural changesin brain regions such asthe nucleus accumbens after exposure to 9-tetrahydrocannabinol, but less is known about cannabis use and brain morphometry in these regions in humans.We collected high-resolution MRI scans on young adult recreational marijuana users and nonusing controls and conducted three independent analyses of morphometry in these structures: (1) gray matter density using voxel-based morphometry, (2) volume (total brain and regional volumes), and (3) shape (surface morphometry). Gray matter density analyses revealed greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only. Significant shape differences were detected in the left nucleus accumbens and right amygdala. The left nucleus accumbens showed salient exposuredependent alterations across all three measures and an altered multimodal relationship across measures in the marijuana group. These data suggest that marijuana exposure, even in young recreational users, is associated with exposure-dependent alterations of the neural matrix of core reward structures and is consistent with animal studies of changes in dendritic arborization. 


Key words: cannabis; gray matter density; marijuana; multimodal imaging; reward; topology/shape 

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