Cannabis Use Patterns in First Episode Psychosis and Schizophrenia: A Scoping Review and Case Series

Cannabis use is associated with psychosis development and symptom relapse in persons with schizophrenia spectrum disorders (SCZ). As more U.S. states legalize cannabis and products increase in potency, it is crucial to better understand recent cannabis use patterns in SCZ.

Methods

We conducted a scoping review of research on cannabis use patterns in SCZ after January 2016 and present a case series of cannabis use in six inpatients with psychosis from 2023–2024.

Results

Scoping review: Of 672 references, nine studies (775 participants) were included; none were designed to characterize cannabis quantity, frequency, or type of use over time. Cannabis measurement methodology varied widely and most studies did not follow recommendations for measuring cannabis use. Frequency and quantity of use at study baseline were reported by most studies and these ranged widely. At least a minority of participants with SCZ in each study used cannabis very frequently; quantity of used ranged widely from 0.6±0.6 to 3.4±2.2 joints/day. One small study detailed cannabis product type among users for THC (93% flower, 80% edibles, 60% concentrates) and CBD (40% flower, 20% edibles, 20% concentrates, 13% oils).

Case Series

Participants were inpatients (32.0±14.4 years; 83.3% diagnosed with SCZ) who used cannabis 2.7±2.1 days/week. All used cannabis leaf (3.1±2.3 joints/day); half (all heavy users) also used concentrates (33.3%) or edibles (16.7%).

Conclusion

Only nine recent studies measured cannabis use patterns in SCZ; methodologies varied. As cannabis legalization expands and product potency increases, further research should characterize cannabis use and its consequences in SCZ.