Evidence-Based Reviews

Cannabidiol (CBD) for schizophrenia: Promise or pipe dream?

Current Psychiatry. 2019 May;18(5):12-16,19-20

References

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9. Schwarz G, Karajgi B. Improvement in refractory psychosis with dronabinol: four case reports. J Clin Psychiatry. 2010;71(11):1552-1553.
10. Schwarz G, Karajgi B, McCarthy R. Synthetic delta-9-tetrahydrocannabinol (dronabinol) can improve the symptoms of schizophrenia. J Clin Psychopharmacol. 2009;29(3):255-258.
11. Meltzer HY, Arvanitis L, Bauer D, et al. Placebo-controlled evaluation of four novel compounds for the treatment of schizophrenia and schizoaffective disorder. Am J Psychiatry. 2004;161(6):975-984.
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13. Kelly DL, Gorelick DA, Conley RR, et al. Effects of cannabinoid-1 receptor antagonist rimonabant on psychiatric symptoms in overweight people with schizophrenia: a randomized, double-blind, pilot study. J Clin Psychopharmacol. 2011;31(1):86-91.
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Clinical stability. Within the RCTs, the greatest response was observed in the study that enrolled patients who were hospitalized with acute symptoms of schizophrenia.²³ In the 2 studies that found either modest or no benefit with CBD, the patients had been stabilized on antipsychotic medications prior to randomization. Cannabidiol may offer limited benefit as add-on therapy to patients who have already responded to antipsychotic treatment, where there is “less room” for additional improvement.

Monotherapy. Both the case reports^22,23 and the RCT with the most robust positive findings²⁴ involved treatment with CBD as monotherapy. For some patients with schizophrenia, CBD might be effective as standalone therapy as an alternative to antipsychotics that is better tolerated. Adding CBD to antipsychotic therapy might be redundant and therefore less effective.

Answering questions about CBD

Cannabidiol is becoming increasingly popular for its purported health benefits. The mixed results of the few studies published on CBD for schizophrenia place clinicians in a difficult position when attempting to answer questions about how cannabinoids might fit into treatment of patients with psychosis. Consider the following:

Is cannabis helpful for patients with schizophrenia? No. Aside from the few case reports suggesting that FDA-approved THC (dronabinol) can improve symptoms in some patients,^9,10 most of the evidence from anecdotal reports and both experimental and observational studies indicate that cannabis, THC, and synthetic cannabinoids have a harmful effect in patients with or at risk for psychosis.^1-3

If you are considering recommending some form of cannabis to patients with schizophrenia, what kind should you recommend? Recommending or encouraging cannabis use for patients with psychosis is ill-advised. Although certain types of cannabis might contain more THC (eg, Cannabis indica vs Cannabis sativa) or variable amounts of CBD, in general the amount of CBD in whole leaf cannabis is minimal, with the ratio of THC to CBD increasingly significantly over the past decade.^3,27 Most forms of cannabis should therefore be avoided by individuals with or at risk for psychotic disorders.

Continue to: What about CBD oil and other CBD products sold in dispensaries?

Cannabidiol (CBD) for schizophrenia: Promise or pipe dream?

References

Answering questions about CBD

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