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. 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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Relation Between Cannabis Use and Subcortical Volumes in People at Clinical High Risk of Psychosis

Lisa Buchy et al. Psychiatry Res Neuroimaging. .
Free PMC article

Abstract

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.

Keywords: Amygdala; Hippocampus; Magnetic resonance imaging; Marijuana; Neuroanatomy; Schizophrenia; Thalamus.

Conflict of interest statement

All authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Estimated marginal means of age-corrected z-scores for clinical high risk cannabis users (n=132) and cannabis non-users (n=387) for thalamus, hippocampus and amygdala, adjusted for intracranial volume. Significantly smaller amygdala volumes were seen in CHR cannabis users compared to CHR non-users. Dotted line represents the approximate mean value of healthy controls.
Figure 2
Figure 2
Estimated marginal means of age-corrected z-scores for clinical high risk participants who endorsed using alcohol at a ‘use without impairment’ severity level (cannabis users, n=100, and cannabis non-users, n=110) for thalamus, hippocampus and amygdala, adjusted for intracranial volume. Significantly smaller hippocampi were seen in CHR cannabis users compared to CHR non-users. Dotted line represents the approximate mean value of healthy controls.

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