Systematic review finds limited evidence for CBD as an antipsychotic, but a favorable side effect profile | Research

The takeaway

A systematic review of 8 studies involving 210 participants found limited evidence that CBD has antipsychotic effects and no evidence that it improves cognition or functioning, though it was well tolerated with fewer side effects than standard antipsychotics.

Psychiatrists, psychosis researchers, and patients interested in alternative treatments.

8 studies, 210 participants: limited efficacy but favorable safety

What the researchers found

CBD showed limited antipsychotic efficacy across studies, with no evidence supporting cognitive or functional benefits. However, CBD had a notably advantageous side effect profile compared to standard antipsychotics and was well tolerated across all studies.

Why it matters

Current antipsychotics often have significant side effects that reduce adherence. If CBD could serve as an adjunctive treatment with fewer side effects, it might improve tolerability even if its direct antipsychotic effects are modest.

The numbers in context

8 eligible studies, 210 total participants. Observational studies had higher risk of bias than experimental studies.

How the study worked

Systematic review searching CINAHL, EBM, EMBASE, MEDLINE, and PubMed from 1970 to 2019 for experimental and observational studies evaluating CBD's antipsychotic and cognitive properties in people with psychotic disorders.

What this study cannot tell us

Small total sample across studies. Heterogeneous study designs, dosing, and participant criteria make comparison difficult. Risk of bias was higher in observational studies.

How to read the evidence

Moderate: systematic review methodology, but limited by small total sample and heterogeneous included studies.

When this study was published

Published in 2020 in Psychiatry Research.

The bigger picture

The gap between CBD's favorable safety profile and its limited demonstrated efficacy highlights the need for larger, better-designed trials before CBD can be recommended as a psychosis treatment.

Questions still open

Would higher CBD doses or longer treatment durations show stronger antipsychotic effects? Is CBD more useful as an adjunct to existing antipsychotics rather than a standalone treatment?

Common questions

Can CBD replace antipsychotic medications?

Based on current evidence, no. The review found limited evidence for antipsychotic efficacy. CBD's main advantage was fewer side effects, which might make it useful as an add-on treatment rather than a replacement.

Why were results so variable across studies?

Studies differed in CBD dosing, treatment duration, whether CBD was used alone or added to existing medications, and which patients were included. These differences make it hard to draw firm conclusions.

Read the original research

Cannabidiol for the treatment of psychosis among patients with schizophrenia and other primary psychotic disorders: A systematic review with a risk of bias assessment.

Psychiatry research, 286, 112890

View on PubMed ↗Publisher’s paper ↗

Citation

Ghabrash, Maykel Farag; Coronado-Montoya, Stephanie; Aoun, John; Gagné, Andrée-Anne; Mansour, Flavi; Ouellet-Plamondon, Clairélaine; Trépanier, Annie; Jutras-Aswad, Didier. (2020). Cannabidiol for the treatment of psychosis among patients with schizophrenia and other primary psychotic disorders: A systematic review with a risk of bias assessment.. Psychiatry research, 286, 112890. https://doi.org/10.1016/j.psychres.2020.112890