Table 1.
The Effect of CBD on Schizophrenia-Related Symptoms in Clinical Studies
| Study Population | Study Design | CBD Dose | Effect | Ref |
|---|---|---|---|---|
| Patients with schizophrenia (n = 39) | Randomized, double-blinded, parallel group, active-controlled study | 800 mg/d oral gelatin capsule of CBD or amisulpride for 4 weeks | Reduction of PANSS and BPRS for positive and negative symptoms of schizophrenia over the baseline | 8 |
| Patients with schizophrenia (n = 42) | Randomized, double-blind, active-controlled, parallel group study | 800 mg/d oral gelatin capsule of CBD or amisulpride for 4 weeks | An improvement in visual memory, processing speed, visuomotor coordination, and sustained attention | 9 |
| Patients with chronic schizophrenia (n = 88) | Multicenter, exploratory, prospective, randomized, parallel group, double-blind, placebo-controlled study | 1000 mg/d oral solution of CBD for 6 weeks | Reduction of PANSS for positive psychotic symptoms of schizophrenia | 10 |
| Patients with schizophrenia (n = 28) | Three parallel-arm, double-blind, placebo control study | Single dose of 300 or 600 mg oral gelatin capsule of CBD | No significant improvement in cognitive performance | 36 |
| Patients with chronic schizophrenia (n = 36) | Randomized, double-blind, placebo-controlled, add-on, parallel group study | 600 mg/d oral gelatin capsule of CBD for 6 weeks | No significant reduction in PANSS and MCCB for psychotic symptoms and cognitive performance | 37 |
| Patients with acute exacerbated schizophrenia (n = 1) | Open-label trial | 1500 mg/d oral gelatin capsule of CBD for 4 weeks | Reduction in BPRS for positive symptoms of schizophrenia | 40 |
| Patients with treatment-resistant schizophrenia (n = 1) | Open-label trial | 750 mg of CBD twice daily for 8 months | Reduction in PANSS for positive and negative psychotic symptoms of schizophrenia | 11 |
| Patients with treatment-resistant schizophrenia (n = 3) | Open-label case series trial | 40 mg/ day with the dose being increased every 5 days up to 1280 mg/d over 30 days | No significant reduction in psychotic symptoms | 41 |
| Patients with anxiety and positive psychotic symptoms (n = 1) | Open-label trial | 800 mg/d of CBD for 6 months | A clinically significant improvement in anxiety and positive psychotic symptoms | 42 |
| Patients with early psychosis (n = 13) | Experimental single dose clinical trials | Single oral dose of 600 mg oral gelatin capsule of CBD | Reduction in psychotic symptoms and an increase in hippocampal glutamate | 43 |
| Patients with clinical high risk (CHR) of psychosis (n = 33) | Experimental single dose clinical trials | Single oral dose of 600 mg oral gelatin capsule of CBD | CBD normalized the abnormal function in the striatum, midbrain, and hippocampus regions of the brain | 44 |
| Patients with CHR of psychosis (n = 33) | Experimental single dose clinical trials | Single oral dose of 600 mg oral gelatin capsule of CBD | Reduction in the abnormal activation in the left insula/parietal operculum | 45 |
| Patients with chronic schizophrenia (n = 72) | Randomized, double-blind, 2-period crossover trial | 800 mg/d of CBD (4 + 2 + 4 weeks) | Ongoing clinical trial | NCT02504151 |
| Patients with chronic schizophrenia (n = 180) | Multicenter, double-blind, 2-arm, placebo control, randomized add-on trial | 800 mg/d of CBD for 26 weeks | Ongoing clinical trial | NCT02926859 |
Note: BPRS, Brief Psychiatric Rating Scale; CBD, cannabidiol; CHR, clinical high risk; MCCB, MATRICS Consensus Cognitive Battery; PANSS, Positive and Negative Syndrome Scale.