No Antipsychotic Was Clearly Better Than Risperidone for Psychosis Patients Who Also Use Substances | Research

The takeaway

A Cochrane review of 8 trials (1,073 participants) found no clear differences between risperidone and other antipsychotics for people with dual diagnosis, though clozapine showed lower cannabis craving in one small trial.

Psychiatrists treating dual diagnosis patients, psychopharmacology researchers.

Up to 75% of people with serious mental illness have co-occurring substance use, yet evidence to guide antipsychotic choice in this population remains very low quality.

What the researchers found

No clear differences between risperidone and clozapine, olanzapine, perphenazine, quetiapine, or ziprasidone on psychotic symptoms, substance use reduction, or study completion in dual diagnosis patients. One small trial (n=28) found clozapine was associated with lower cannabis craving than risperidone.

Why it matters

Up to 75% of people with serious mental illness have co-occurring substance use disorders. Clinicians need evidence to guide antipsychotic choice in this common scenario, but this review found the evidence base is insufficient to make recommendations.

The numbers in context

8 RCTs, 1,073 participants. All evidence rated very low to low quality by GRADE criteria. Clozapine showed lower cannabis craving (MD 7.00, 95% CI 2.37-11.63) in one trial of 28 patients.

How the study worked

Cochrane systematic review of 8 RCTs with 1,073 participants comparing risperidone to other antipsychotics in people with serious mental illness and co-occurring substance misuse. GRADE quality assessment applied.

What this study cannot tell us

Very low to low quality evidence throughout. Most trials were small, secondary analyses of larger studies, or subgroup analyses. Heterogeneous study designs. Missing data on important outcomes like metabolic effects and quality of life.

How to read the evidence

Preliminary - Cochrane review is rigorous methodology, but all available evidence was rated very low to low quality by GRADE standards.

When this study was published

Published in 2018. Literature searched through October 2017.

The bigger picture

The absence of good evidence for antipsychotic choice in dual diagnosis is a significant gap given how common this comorbidity is. The hint that clozapine may reduce cannabis craving is intriguing but needs replication.

Questions still open

Does clozapine genuinely reduce cannabis craving more than other antipsychotics? Would larger, purpose-designed trials find meaningful differences? Should antipsychotic selection in dual diagnosis prioritize substance use outcomes?

Common questions

Which antipsychotic is best for patients who also use cannabis?

This Cochrane review found insufficient evidence to recommend one antipsychotic over another for dual diagnosis patients. One small trial suggested clozapine might reduce cannabis craving more than risperidone, but this needs confirmation.

How common is dual diagnosis (mental illness plus substance use)?

Up to 75% of people with serious mental illness like schizophrenia have co-occurring substance use disorders, making dual diagnosis the norm rather than the exception. Despite this, evidence for optimal treatment is lacking.

Read the original research

Risperidone versus other antipsychotics for people with severe mental illness and co-occurring substance misuse.

The Cochrane database of systematic reviews, 1(1), CD011057

View on PubMed ↗Publisher’s paper ↗

Citation

Temmingh, Henk S; Williams, Taryn; Siegfried, Nandi; Stein, Dan J. (2018). Risperidone versus other antipsychotics for people with severe mental illness and co-occurring substance misuse.. The Cochrane database of systematic reviews, 1(1), CD011057. https://doi.org/10.1002/14651858.CD011057.pub2