Joseph M. Pierre, MD Health Sciences Clinical Professor Department of Psychiatry and Biobehavioral Sciences David Geffen School of Medicine University of California, Los Angeles Los Angeles, California
Disclosure The author reports no financial relationships with any companies whose products are mentioned in this article, or with manufacturers of competing products.
What about CBD oil and other CBD products sold in dispensaries?Cannabidiol is increasingly available in various forms based on its ability to be designated as a legal hemp product (containing <0.3% THC) at the federal level or as a cannabinoid in states where cannabis is legal.However, several studies have now shown that cannabis products sold online or in dispensaries are often labeled inaccurately, with both under- and over-reporting of THC and CBD content.28-30 Some CBD products have been found to have almost no CBD at all.29,30 The unreliability of product labeling makes it difficult to predict the effects of CBD products that are not subject to FDA purity standards for medications or dietary supplements. It also raises questions about the sources of CBD and the reliability of dosing in the studies discussed above.
Why might CBD work as an antipsychotic?Although CBD has minimal affinity for cannabinoid receptors, it appears to act as a partial agonist of dopamine D2 receptors and an agonist at 5-HT1A receptors, with overall effects that decrease mesolimbic dopamine activity.31,32 In addition, CBD increases the availability of the endogenous cannabinoid anandamide, which may have antipsychotic properties.14,33
Now that the FDA has approved CBD manufactured by a pharmaceutical company, should it be prescribed “off-label” for patients with schizophrenia?This is the “million dollar question,” with insufficient evidence to provide a clear answer.It should now be possible to prescribe FDA-approved CBD for off-label purposes, including the treatment of schizophrenia and other psychiatric disorders. No doubt, some clinicians are already doing so. This will predictably yield more anecdotal evidence about efficacy and adverse effects in the future, but there is not yet adequate evidence to support an FDA indication for CBD in schizophrenia. Additional studies of CBD for schizophrenia are ongoing.
Bottom Line
Cannabidiol (CBD) is becoming increasingly popular based on its purported health benefits, but the evidence supporting a therapeutic role in psychiatry is preliminary at best. Although CBD is now available by prescription as an FDA-approved drug for the treatment of 2 rare forms of epilepsy, its benefits in patients with schizophrenia are uncertain based on mixed results in clinical trials.
