How does recent cannabis use affect symptoms in first-episode psychosis? | Research

The takeaway

Among 247 first-episode psychosis patients, those who had used cannabis in the prior three months showed less anhedonia-asociality but more severe delusions and bizarre behavior, with no differences in cognitive functioning.

Clinicians treating first-episode psychosis in cannabis users, and researchers studying how substance use interacts with psychotic symptom profiles.

Less anhedonia, more delusions

What the researchers found

Cannabis users had significantly lower anhedonia-asociality scores (10.7 vs 12.1, p=0.023) but more severe delusions (19.3 vs 15.9, p=0.005) and bizarre behavior (p=0.01). No significant differences appeared across nine MATRICS cognitive battery measures. Cannabis dose did not correlate with any symptom or cognitive measure.

Why it matters

The finding that cannabis use in psychosis is associated with less social withdrawal but more delusions suggests cannabis may have differential effects on different symptom dimensions, rather than making psychosis uniformly better or worse.

The numbers in context

247 patients; 6 psychiatric units; anhedonia-asociality: 10.7 vs 12.1 (p=0.023); delusions: 19.3 vs 15.9 (p=0.005); bizarre behavior significant (p=0.01); no differences across 9 MCCB cognitive measures; no dose-response relationship

How the study worked

Cross-sectional study of 247 first-episode psychosis patients from six inpatient psychiatric units (2008-2013). Cannabis use assessed via Longitudinal Substance Use Recall. Symptoms measured with SANS and SAPS. Cognition assessed with the MATRICS Consensus Cognitive Battery.

What this study cannot tell us

Cross-sectional; cannot determine if cannabis caused symptom differences or if pre-existing symptom profiles influenced cannabis use. Hospital-based sample during acute episodes. Self-reported cannabis use.

How to read the evidence

Moderately large clinical sample with validated measures, but cross-sectional design limits causal inference.

When this study was published

Published in 2021 with data from 2008-2013; cannabis potency has increased since.

The bigger picture

The reduced anhedonia in cannabis users is intriguing. It could mean cannabis helps with social withdrawal, or that people with less anhedonia are more likely to seek out cannabis. Either way, the pattern suggests cannabis users with psychosis may represent a distinct clinical subgroup.

Questions still open

Does cannabis genuinely reduce anhedonia in psychosis, or do less anhedonic patients simply use more cannabis? Would targeting cannabis use in this population worsen negative symptoms? Could this symptom profile distinguish cannabis-related from non-cannabis psychosis?

Common questions

Does cannabis make psychosis better or worse?

Neither simply. This study found cannabis users had less social withdrawal (a positive sign) but more severe delusions and bizarre behavior. The effects appear to differ across symptom types rather than being uniformly harmful or helpful.

Does cannabis affect thinking ability in psychosis?

No differences were found across nine cognitive measures between cannabis-using and non-using psychosis patients, suggesting cannabis did not add to the cognitive deficits already present in psychosis.

Read the original research

Symptomatology and neurocognition among first-episode psychosis patients with and without cannabis use in the three months prior to first hospitalization.

Schizophrenia research, 228, 83-88

View on PubMed ↗Publisher’s paper ↗

Citation

Pope, Leah G; Manseau, Marc W; Kelley, Mary E; Compton, Michael T. (2021). Symptomatology and neurocognition among first-episode psychosis patients with and without cannabis use in the three months prior to first hospitalization.. Schizophrenia research, 228, 83-88. https://doi.org/10.1016/j.schres.2020.12.012