Preclinical and Clinical Evidence Supporting Use of Cannabidiol in Psychiatry

Table 1

Clinical studies investigating CBD effects in schizophrenic patients.

Psychiatric disorder	Study design	Population	Treatment	Endpoints	Outcome	Reference
Acute schizophrenia	Randomized, double-blinded, monocenter, parallel-group, controlled clinical trial	Sample: 42 acutely exacerbated schizophrenic (men and women) patients aging 18–50 years were enrolled	CBD or amisulpride starting with 200 mg per day each and increased stepwise by 200 mg per day to a daily dose of 200 mg four times daily (total 800 mg per day)	BPRS and PANSS were both used as primary outcome measures for the assessment of psychotic symptoms at baseline, days 14 and 28 of the treatment period; Serum anandamide levels; Side effects were evaluated using EPS, measurement of serum prolactin and body weight	CBD treatment produced clinical improvement accompanied by a significant increase in serum anandamide levels	Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia; Leweke et al. [35]
Schizophrenia or a related psychotic disorder	Multicenter, double-blind, randomized, placebo-controlled, parallel-group trial	Sample: 51 patients; CBD group: N = 43; placebo group: N = 45. Total sample mean age: 40.8, SD: 11.69 years	Patients were randomly assigned in a 1 : 1 ratio to receive CBD 1,000 mg/day or matching placebo alongside the existing antipsychotic medication, administered in two divided doses (morning and evening) for 6 weeks	Positive psychotic symptoms (measured using the PANSS positive subscale); Scale for the Assessment of Negative Symptoms (SANS) score; Clinical Global Impressions Scale (CGI-I); Global Assessment of Functioning (GAF) Scale score; Brief Assessment of Cognition in Schizophrenia (BACS); Carer Global Impression of Change Scale; Simpson-Angus Scale; body weight, waist measurement, BMI, and HDL cholesterol levels	The CBD group had lower levels of positive psychotic symptoms and were more likely to have been rated as improved and as not severely unwell by the treating clinician. Patients who received CBD also showed greater improvements that fell short of statistical significance in cognitive performance and in overall functioning. CBD was well tolerated, and rates of adverse events were similar between the CBD and placebo groups	Cannabidiol (CBD) as an adjunctive therapy in schizophrenia: a multicenter randomized controlled trial; McGuire et al. [36]

CBD: cannabidiol; BPRS: Brief Psychiatric Rating Scale; EPS: Extrapyramidal Symptom Scale; PANSS: Positive and Negative Syndrome Scale; PANSS is a medical scale used for measuring symptom severity of patients with schizophrenia.