Cannabis Use Patterns in First Episode Psychosis and Schizophrenia: A Scoping Review and Case Series
Jeff W. Jin, Nolan J. Neu, Isaac B. Satz, Janelle Annor, Mohamed E Elsayed, Mary F. Brunette
preprint DOI: 10.1101/2025.04.28.25325846 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Scoping review with case series Case report |
|---|---|
| Sample size | 781 |
| Population | People with schizophrenia spectrum disorders in the reviewed studies; six inpatients with psychosis (mean age 32.0 years, 83.3% diagnosed with schizophrenia spectrum disorders) in the case series |
| Topics | Cannabis |
| Key findings | Only nine studies published after January 2016 measured cannabis use patterns in schizophrenia spectrum disorders, and none were designed to characterize quantity, frequency, or product type over time, with measurement methods varying widely. Reported use ranged widely, from 0.6 to 3.4 joints per day across studies, and the case series found use on 2.7 days per week and 3.1 joints per day, with half of patients also using concentrates or edibles. The authors argue that further research should characterize cannabis use and its consequences as legalization expands and potency increases. |
Abstract
Background: 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.
Comparable studies
Other case reports and case series on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psychotic Reactions Following Cannabis Use in East Indians Patients at an Indian drug addiction clinic who developed acute cannabis-related psychosis | 1974 | Descriptive report (case series of clinical observations) | n = 200 |
| Psychiatric effects of cannabis use Swedish cases of cannabis psychosis | 1985 | Case series | n = 70 |
| Forty-Six Cases of Psychosis in Cannabis Abusers Gunila Bernhardson Habitual cannabis users treated for psychosis at Swedish psychiatric clinics and mental... | 1972 | Case series (retrospective survey of psychiatric records) | n = 46 |
| Hallucinogen persisting perception disorder after psilocybin consumption: a case study 18-year-old man with HPPD after mixed psilocybin and cannabis intoxication | 2005 | Case study | n = 1 |
| Cannabis‐induced Koro in Americans American men aged 22-26 with years of cannabis experience who reported negative... | 2001 | Case series | n = 3 |
Citations in the library
Cites 15
- Acute and chronic effects of cannabinoids on effort-related decision-making and reward learning: an evaluation of the cannabis ‘amotivational’ hypotheses Psychopharmacology September 2, 2016
- Poor medication adherence and risk of relapse associated with continued cannabis use in patients with first-episode psychosis: a prospective analysis The Lancet Psychiatry July 10, 2017
- Daily use of high-potency cannabis is associated with more positive symptoms in first-episode psychosis patients: the EU-GEI case–control study Psychological Medicine March 18, 2020
- Randomized Laboratory Study of Single-Dose Cannabis, Dronabinol, and Placebo in Patients With Schizophrenia and Cannabis Use Disorder Schizophrenia Bulletin June 20, 2024
- Changes in Incident Schizophrenia Diagnoses Associated With Cannabis Use Disorder After Cannabis Legalization JAMA Network Open February 1, 2025
and 10 more in the library