A JAMA Psychiatry meta-analysis of 35 trials found that current psychological and psychosocial interventions provided limited benefit for reducing symptoms and no effect on reducing substance use in people with co-occurring schizophrenia and substance use disorders, except for a small effect on nicotine use.
Clinicians treating co-occurring schizophrenia and substance use, and policymakers planning mental health services.
Current psychological interventions showed no effect on cannabis, alcohol, or stimulant use in people with schizophrenia
What the researchers found
A very small effect favoring interventions was observed for overall symptoms (SMD -0.11, 95% CI -0.27 to 0.05, low confidence), mainly driven by nicotine studies. No difference was found for all types of substance use combined (SMD -0.01, 95% CI -0.21 to 0.18, moderate confidence). Alcohol, cannabis, amphetamines, and other stimulants separately showed no effect. Only nicotine showed a small treatment effect.
Why it matters
About 42% of people with schizophrenia have co-occurring substance use disorders, yet they are frequently excluded from clinical trials. This comprehensive meta-analysis reveals that current evidence-based psychological treatments are essentially ineffective for this doubly burdened population, highlighting an urgent unmet treatment need.
The numbers in context
35 RCTs, 4,136 participants (25.4% female, mean age 37.2 years). Overall symptoms: SMD -0.11 (low confidence). Substance use reduction: SMD -0.01 (moderate confidence). Alcohol, cannabis, amphetamines, stimulants: no significant effects. Only nicotine showed a small positive effect.
How the study worked
Systematic review and random-effect pairwise meta-analysis of 35 RCTs (4,136 participants). Cochrane Schizophrenia Group registry searched to January 2025. GRADE confidence ratings applied. No restrictions on substance type. Published in JAMA Psychiatry.
What this study cannot tell us
Meta-analysis is limited by the quality of included studies. Heterogeneity across intervention types, substances, and populations may mask effects in subgroups. The null finding for cannabis specifically may reflect limited studies targeting cannabis use in schizophrenia.
How to read the evidence
Comprehensive meta-analysis published in JAMA Psychiatry with GRADE confidence ratings, representing the highest available evidence synthesis.
When this study was published
Published in 2026, with searches through January 2025.
The bigger picture
Published in JAMA Psychiatry, this meta-analysis carries considerable weight and effectively calls for a paradigm shift in how we treat this population. If standard psychological interventions do not work, new approaches, whether pharmacological, digital, integrated care models, or novel psychotherapies, are urgently needed.
Questions still open
- What novel interventions might work for this population? Would integrated pharmacological and psychological approaches be more effective? Are there specific subgroups (by substance, symptom severity, or intervention type) where effects might emerge?
Common questions
Do current treatments work for people with schizophrenia who also use substances?
Why is this population so difficult to treat?
Read the original research
Psychological and Psychosocial Interventions for People With Schizophrenia and Co-Occurring Substance Use Disorders: A Systematic Review and Meta-Analysis.
JAMA psychiatry
Citation
Salahuddin, Nurul Husna; Herlitzius, Emilia; Schütz, Alexandra; Siafis, Spyridon; Priller, Josef; Leucht, Stefan; Bighelli, Irene. (2026). Psychological and Psychosocial Interventions for People With Schizophrenia and Co-Occurring Substance Use Disorders: A Systematic Review and Meta-Analysis.. JAMA psychiatry. https://doi.org/10.1001/jamapsychiatry.2025.4390
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