Persistent cannabis use predicted worse outcomes in young adults with first-episode psychosis | Research

The takeaway

Among 938 young adults with first-episode psychosis, nearly one-third had persistent cannabis use at one year, and they had worse symptoms than those who stopped or never used.

Early psychosis clinicians, addiction specialists, and first-episode psychosis program designers.

32.8% persistent cannabis use at 1 year; reducing use improved symptoms (p=0.008)

What the researchers found

Of 938 first-episode psychosis patients in Coordinated Specialty Care, 38.8% used cannabis at admission and 32.8% had persistent use at 1 year. Persistent users were more likely male, had worse baseline symptoms, more suicidality, violent ideation, and legal trouble. At 1 year, persistent users maintained worse symptoms than non-users, while those who reduced use showed significant symptom improvement.

Why it matters

One-third of first-episode psychosis patients continued using cannabis despite receiving specialized early intervention services. The finding that reducing use improved symptoms provides concrete motivation for cannabis-focused interventions in this population.

The numbers in context

938 patients; 38.8% used cannabis at admission; 32.8% persistent use at 1 year; persistent users had worse GAF scores at baseline (p<0.001) and 1 year (p=0.021); reduced users improved vs. persistent (p=0.008).

How the study worked

Longitudinal analysis of 938 first-episode psychosis patients enrolled in US Coordinated Specialty Care programs for at least 1 year, categorized into no use, reduced use, and persistent cannabis use groups.

What this study cannot tell us

Observational (cannot prove cannabis caused worse outcomes); selection effects (those able to reduce may differ in other ways); cannabis use self-reported; limited to US CSC programs.

How to read the evidence

Moderate: large real-world sample with longitudinal follow-up, but observational design limits causal inference.

When this study was published

Published 2020.

The bigger picture

This study from real-world US clinical settings shows that even evidence-based early psychosis programs have limited impact on cannabis use. The clear symptom improvements in those who did reduce suggest that cannabis interventions should be a core component of early psychosis care.

Questions still open

What interventions most effectively reduce cannabis use in early psychosis? Would mandatory cannabis screening improve CSC outcomes?

Common questions

Does cannabis worsen psychosis outcomes?

In this study, persistent cannabis users had worse symptoms at 1 year. Importantly, those who reduced their use showed significant symptom improvement, suggesting the relationship may be modifiable.

How common is cannabis use in first-episode psychosis?

Nearly 39% used cannabis at admission, and about one-third continued persistent use at 1 year despite receiving specialized early intervention services.

Read the original research

Persistent cannabis use among young adults with early psychosis receiving coordinated specialty care in the United States.

Schizophrenia research, 222, 274-282

View on PubMed ↗Publisher’s paper ↗

Citation

Marino, Leslie; Scodes, Jennifer; Richkin, Talia; Alves-Bradford, Jean-Marie; Nossel, Ilana; Wall, Melanie; Dixon, Lisa. (2020). Persistent cannabis use among young adults with early psychosis receiving coordinated specialty care in the United States.. Schizophrenia research, 222, 274-282. https://doi.org/10.1016/j.schres.2020.05.035