Cannabis-associated psychosis linked to better cognitive function, but use may cause relapse

Males hospitalized for new-onset psychosis with confirmed cannabis exposure (CAP) demonstrate better cognitive function, lower cortical excitatory/inhibitory (E/I) balance, fewer negative symptoms, and greater improvement in mood symptoms than those with noncannabis-associated psychosis (NCAP), a study has shown. However, resuming cannabis use may result in relapse.

This prospective study compared CAP (n=66) with NCAP (n=53) and assessed participants at admission and after 4 weeks of standardized inpatient treatment using cognitive tests (CogState Schizophrenia Battery, Hopkins Verbal Learning Test), electroencephalography (EEG), and symptom scales (Positive and Negative Syndrome Scale [PANSS], Calgary Depression Rating Scale [CDRS], Young Mania Rating Scale [YMRS]).

Cognitive test performance improved significantly in the CAP group but not in the NCAP group, despite the absence of group differences at admission.

The CAP group also had significantly higher power spectral density exponent in the EEG, a proxy index of cortical E/I balance, as well as lower PANSS negative and total scores but greater depressive (CDRS) and manic (YMRS) symptoms than the NCAP group at admission.

Both groups showed improved psychosis symptoms with treatment, but the CAP group had greater improvement in mood symptoms.

During follow-up, 10 of 16 CAP participants with available data were rehospitalized for psychosis exacerbation after resuming cannabis use. On the other hand, relapse rarely occurred among participants who remained abstinent.

“Together, these results raise the possibility that cannabis-associated psychosis is a distinct subtype of first-episode psychosis,” the investigators said. “Given the increasing rates of psychosis related to cannabis, further studies are needed to examine its long-term trajectory and refine treatment approaches.”