Cannabis Use Was Linked to Reduced Cingulate Brain Volume in Both Early Psychosis and At-Risk Patients | Research

The takeaway

Current cannabis use was associated with reduced gray matter volume in the cingulate cortex, a brain region rich in CB1 receptors and implicated in schizophrenia, in both first-episode psychosis and at-risk patients.

Read this if you are at risk for or have experienced a psychotic episode and use cannabis.

Cingulate volume reduction from cannabis was independent of psychosis stage

What the researchers found

Researchers performed MRI brain scans on 23 first-episode psychosis (FEP) and 37 at-risk mental state (ARMS) patients, manually tracing the cingulate cortex. After controlling for age, gender, alcohol, brain volume, and antipsychotic medication, current cannabis use was negatively associated with cingulate volume.

Specifically, the posterior cingulate was reduced bilaterally in cannabis users regardless of diagnostic group. The left anterior cingulate was also reduced. These effects were independent of diagnosis, meaning cannabis appeared to affect this brain region similarly in both at-risk and first-episode patients. The cingulate cortex is rich in CB1 cannabinoid receptors, providing a biological explanation for the finding.

Why it matters

The cingulate cortex is one of the key brain regions implicated in schizophrenia. Finding that cannabis use is associated with reduced volume in this region across both at-risk and first-episode groups suggests cannabis may compound the brain changes associated with psychosis vulnerability.

The numbers in context

23 FEP + 37 ARMS patients. Posterior cingulate: reduced bilaterally in cannabis users. Left anterior cingulate: reduced in cannabis users. Effects independent of diagnostic group and all covariates.

How the study worked

Cross-sectional MRI study. 23 FEP and 37 ARMS subjects. Manual tracing of anterior and posterior cingulate cortex bilaterally. Cannabis use assessed with Basel Interview for Psychosis. Repeated measures ANCOVA controlling for covariates.

What this study cannot tell us

Cross-sectional design cannot determine whether cannabis caused volume reduction or vice versa. Small sample sizes within each group. Manual tracing is reliable but operator-dependent. No healthy control comparison. Cannabis use was self-reported.

How to read the evidence

Small cross-sectional MRI study; preliminary evidence for cannabis-related structural changes in a psychosis-relevant brain region.

When this study was published

Published in 2013. Neuroimaging studies of cannabis and psychosis have continued with larger cohorts.

The bigger picture

This study is notable because the cannabis effect was consistent across diagnostic stages (at-risk and first-episode). This suggests cannabis may affect the cingulate cortex regardless of whether psychosis has fully manifested, potentially contributing to disease progression.

Questions still open

Does cingulate volume reduction precede or follow cannabis use? Would cessation allow volume recovery? Does this structural change predict clinical outcomes? Is the effect specific to THC or do other cannabinoids also affect cingulate volume?

Common questions

Does cannabis shrink the brain in people at risk for psychosis?

This study found that current cannabis use was associated with reduced gray matter in the cingulate cortex, a brain region involved in psychosis. This was true for both people at risk for psychosis and those who already had a first episode. However, the study cannot prove cannabis caused the reduction, and the effect may be reversible with cessation.

Why might the cingulate cortex be particularly affected?

The cingulate cortex has a high density of CB1 cannabinoid receptors, the primary target of THC. Chronic stimulation of these receptors by cannabis could potentially alter the structure of this region. Because the cingulate cortex is also one of the key regions affected in schizophrenia, cannabis-induced changes here could theoretically compound the structural abnormalities that contribute to psychosis.

Read the original research

Cannabis use and brain structural alterations of the cingulate cortex in early psychosis.

Psychiatry research, 214(2), 102-8

View on PubMed ↗Publisher’s paper ↗

Citation

Rapp, Charlotte; Walter, Anna; Studerus, Erich; Bugra, Hilal; Tamagni, Corinne; Röthlisberger, Michel; Borgwardt, Stefan; Aston, Jacqueline; Riecher-Rössler, Anita. (2013). Cannabis use and brain structural alterations of the cingulate cortex in early psychosis.. Psychiatry research, 214(2), 102-8. https://doi.org/10.1016/j.pscychresns.2013.06.006