Cannabis Users in Early Psychosis Who Reduced Use Still Had Worse Outcomes Than Abstainers | Research

The takeaway

In a 3-year study of 467 first-episode psychosis patients, cannabis users who reduced their use showed some improvement in negative symptoms but higher hospitalization rates than abstainers or light users.

early intervention psychosis teams, addiction psychiatrists, substance use researchers

What the researchers found

Alcohol users tended to maintain consumption over time, while some cannabis users reduced their use. Persistent alcohol users had the worst baseline characteristics and outcomes. Abstinent or light cannabis users consistently had better symptom outcomes than persistent or decreased users. However, cannabis decreasers showed higher hospitalization rates than other groups, though their negative symptoms gradually improved to levels similar to abstinent users by program end.

Why it matters

The finding that reducing cannabis use improved some but not all outcomes suggests that simply cutting back may not be sufficient for optimal recovery in first-episode psychosis, and that the trajectory of use matters for treatment planning.

The numbers in context

467 FEP patients over 3 years. Alcohol users maintained consumption. Some cannabis users reduced. Abstinent/light cannabis users: best outcomes. Decreased cannabis users: higher hospitalization but improving negative symptoms. Persistent alcohol: worst outcomes.

How the study worked

3-year early intervention program study of 467 first-episode psychosis patients. Latent class analysis identified cannabis and alcohol use trajectory subgroups. Logistic regressions and mixed-model repeated measures compared baseline characteristics and clinical outcomes across trajectory groups.

What this study cannot tell us

Observational design limits causal inference. Self-reported substance use. Latent class analysis results are sample-dependent. Cannot determine if symptom changes caused use changes or vice versa. Single intervention program setting.

How to read the evidence

Longitudinal design with adequate sample and sophisticated trajectory analysis, but observational nature and self-reported use limit to moderate.

When this study was published

Data from a 3-year early intervention psychosis program.

The bigger picture

This study highlights that alcohol and cannabis use have distinct trajectories and impacts in early psychosis, suggesting that substance-specific interventions may be more effective than generic substance use treatment in this population.

Questions still open

Why did cannabis reducers have higher hospitalization rates?
Should early psychosis programs offer different interventions for alcohol vs. cannabis use?

Common questions

Should people with psychosis stop using cannabis?

Abstinent and light-use groups had consistently better outcomes. Those who reduced use showed some improvement in negative symptoms but still had higher hospitalization rates, suggesting that abstinence or minimal use is associated with the best outcomes.

Is alcohol or cannabis worse for psychosis?

Persistent alcohol users had the worst baseline characteristics and outcomes overall. Cannabis had different patterns: the key finding was that even reducing cannabis use did not fully normalize outcomes compared to abstinence.

Read the original research

Correlates and trajectories of alcohol and cannabis misuse in the early phase of psychosis: Do we need substance specific interventions?

Schizophrenia research, 285, 349-359

View on PubMed ↗Publisher’s paper ↗

Citation

Spanevello, Carolina; Alameda, Luis; Solida, Alessandra; Empson, Lilith Abrahamyan; Alerci, Livia; Mebdouhi, Nadir; Conchon, Caroline; Vieira, Sandra; Golay, Philippe; Conus, Philippe. (2025). Correlates and trajectories of alcohol and cannabis misuse in the early phase of psychosis: Do we need substance specific interventions?. Schizophrenia research, 285, 349-359. https://doi.org/10.1016/j.schres.2025.09.020