Table 1.
Case reports and clinical trials on the efficacy of cannabidiol (CBD) as a treatment for psychotic disorders.
| Study | Study Design | Participants | Substance Use | Intervention | CBD Administration | Primary Outcomes |
|---|---|---|---|---|---|---|
| Zuardi et al. (1995) [51] | Case report | 19-year-old female schizophrenia inpatient (two years after first hospitalization) | Not reported | Progressive increase of CBD monotherapy over four weeks, followed by haloperidol treatment | Oral; up to 1500 mg/day | Improvement of symptomatology. Improvement did not continue on haloperidol.No side effects. |
| Zuardi et al. (2006) [52] | Case series | Three male inpatients with treatment-resistant schizophrenia | Not reported | Progressive increase of CBD monotherapy over four weeks, followed by olanzapine treatment | Oral; up to 1280 mg/day | Mild improvement of symptomatology of one patient after CBD treatment.No side effects. |
| Makiol and Klunge (2019) [53] | Case report | 57-year old-female treatment-resistant schizophrenia inpatient | Not reported | Treatment with CBD adjunctive to clozapine and lamotrigine | Oral; up to 1500 mg/day | Improvement of symptomatology and the patient fulfilled remission criteria with only mild negative symptoms. |
| Leweke et al. (2012) [54] | Double-blind CBD vs. amisulpride RCT | 39 acutely psychotic inpatients | Not reported, exclusion criteria were SUD or positive urine drug screening for illicit drugs in general and cannabis in particular. | Hospitalization and four-week treatment with CBD or amisulpride | Oral; up to 800 mg/day | Treatment with either CBD or amisulpride is associated with improvement of symptomatology, but CBD has a superior side-effect profile. |
| McGuire et al. (2018) [55] | Double-blind placebo RCT | 88 outpatients with schizophrenia | Not reported, substance use was not an exclusion and not prohibited during the study. | A six-week treatment with CBD adjunctive to antipsychotic medication. | Oral solution; 1000 mg/day | Improvement of symptomatology, no side effects. |
| Hallak et al. (2010) [56] | Single dose double-blind placebo RCT | 28 schizophrenia outpatients | Not reported | Acute treatment with a single dose of CBD | Oral; 300 or 600 mg | CBD 300 mg and placebo both improved cognitive performance as compared to CBD 600 mg. No effects on symptomatology. |
| Boggs et al. (2018) [57] | Double-blind placebo RCT | 36 outpatients with chronic schizophrenia | Not reported, patients with substance abuse in the past three months or dependence in the past six months were excluded. | Six-week treatment with CBD added to a stable dose of antipsychotic medication | Oral; 600 mg/day | Cognitive performance improved after placebo, symptomatology improved in both groups, no differences between groups. |
CBD: Cannabidiol; RCT: Randomized clinical trial.