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Psychiatry Res Neuroimaging. 2016 Aug 30;254:3-9. doi: 10.1016/j.pscychresns.2016.06.001. Epub 2016 Jun 2.

Relation between cannabis use and subcortical volumes in people at clinical high risk of psychosis.

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Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada.
University of California, San Francisco, San Francisco, CA, United States.
Department of Psychology, Yale University, New Haven, CT, United States.
Department of Psychiatry, UCSD, La Jolla, CA, United States.
Department of Psychiatry, Zucker Hillside Hospital, Long Island, NY, United States.
Department of Psychiatry, Yale University, New Haven, CT, Unites States.
Department of Psychiatry, University of North Carolina, Chapel Hill, NC, United States.
Department of Psychiatry, Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital, Boston, MA, United States.
Departments of Psychology and Psychiatry, Emory University, Atlanta, GA, United States.
Departments of Psychiatry and Biobehavioral Sciences and Psychology, UCLA, Los Angeles, CA, United States.
Department of Psychiatry, University of Calgary, Calgary, Alberta, Canada. Electronic address:


Among people at genetic risk of schizophrenia, those who use cannabis show smaller thalamic and hippocampal volumes. We evaluated this relationship in people at clinical high risk (CHR) of psychosis. The Alcohol and Drug Use Scale was used to identify 132 CHR cannabis users, the majority of whom were non-dependent cannabis users, 387 CHR non-users, and 204 healthy control non-users, and all participants completed magnetic resonance imaging scans. Volumes of the thalamus, hippocampus and amygdala were extracted with FreeSurfer, and compared across groups. Comparing all CHR participants with healthy control participants revealed no significant differences in volumes of any ROI. However, when comparing CHR users to CHR non-users, a significant ROI×Cannabis group effect emerged: CHR users showed significantly smaller amygdala compared to CHR non-users. However, when limiting analysis to CHR subjects who reported using alcohol at a 'use without impairment' severity level, the amygdala effect was non-significant; rather, smaller hippocampal volumes were seen in CHR cannabis users compared to non-users. Controlling statistically for effects of alcohol and tobacco use rendered all results non-significant. These results highlight the importance of controlling for residual confounding effects of other substance use when examining the relationship between cannabis use and neural structure.


Amygdala; Hippocampus; Magnetic resonance imaging; Marijuana; Neuroanatomy; Schizophrenia; Thalamus

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