The role of cannabidiol oil in schizophrenia treatment. a systematic review and meta-analysis

The purpose of the present meta-analysis was to assess the efficacy of cannabidiol (CBD) oil in patients with schizophrenia. A search was conducted in EMBASE, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to April 24th, 2020. Randomized clinical trials (RCTs), which used CBD oil treatment versus placebo or any other antipsychotic in schizophrenia patients either as monotherapy or add-on therapy, were included. Data were pooled using a random-effects model. The primary outcomes were efficacy as measured by total symptoms of schizophrenia and improvement in cognition. The meta-analysis was registered with PROSPERO [number: CRD42020157146]. Three double-blind RCTs were included. In one study, CBD oil was compared with amisulpride as monotherapy treatment, but no statistically significant difference in overall efficacy was detected between them. No data were available for cognition. The other two studies estimated the effects of CBD oil as add-on treatment compared to placebo; no significant difference was found either in overall efficacy or in cognition. Altogether, insufficient evidence exists on the efficacy and safety of CBD oil in schizophrenia patients. More RCTs, comparing CBD oil with placebo and other antipsychotics are warranted.