Cannabidiol (CBD) Shows Therapeutic Benefits for Schizophrenia

by | May 15, 2018 | 2018, Alternative Therapies, Brain Health, CBD

Written by Angeline A. De Leon, Staff Writer. Compared to the control, participating subjects with schizophrenia had a significantly greater reduction in psychotic symptoms after six weeks of treatment with cannabidiol.

Schizophrenia is a complex, chronic mental disorder involving a break-down in the relation between thought, emotion, and behavior. Affecting about 1% of the population, the exact cause of schizophrenia is unknown, but its effects are severe, resulting in impaired daily functioning, long-term social dysfunction, and a distressing disconnection from reality. First-line of treatment for this mental illness relies heavily on antipsychotic drugs, which act to block dopamine receptors in the brain to help stabilize mood and improve disordered thought. However, antipsychotics demonstrate poor response in almost a third of patients 1 and have been shown to have little effect on cognitive impairment and negative symptoms, such as reduced social interaction and blunted affect 2. New research suggests the potential for a cannabis compound called cannabidiol (CBD) to treat the more challenging symptoms of schizophrenia. Although certain forms of cannabis are thought to trigger psychosis, findings indicate that risk of psychotic symptoms and cognitive impairment is lower when taking strains of cannabis that contain higher relative proportions of CBD to THC 3. CBD demonstrates the ability to reduce THC-induced psychosis in healthy subjects 4 and appears to improve symptoms in schizophrenic patients showing no response to typical antipsychotic medications 5. In one randomized trial, researchers comparing CBD against amisulpride reported that CBD showed similar effectiveness to conventional prescription medicine after just four weeks of treatment, improving mood in patients with acute schizophrenia symptoms and resulting in fewer adverse effects 6. To examine the safety and efficacy of CBD as an adjunctive treatment for schizophrenia, researchers at London’s King College evaluated the impact of CBD on both positive and negative psychotic symptoms, as well as cognition and overall functioning.

A multicenter, double-blind, randomized, placebo-controlled, parallel-group trial was carried out using a group of 86 patients (aged 18-65 years) with schizophrenia or a related psychotic disorder. These participants showed at least a partial response to antipsychotic medication in the past and were receiving a stable dosage of antipsychotic medication for a minimum of four weeks. At baseline and following the treatment phase, participants completed the Positive and Negative Syndrome Scale (PANSS), the Brief Assessment of Cognition in Schizophrenia (BACS), the Global Assessment of Functioning Scale, as well as the improvement and severity scales on the Clinical Global Impressions Scale (CGI-I and CGI-S). Subjects were randomized in a 1:1 ratio to receive either 1,000 mg/day of CBD (10 mL of a 100 mg/mL oral solution) or matching placebo taken in divided doses, once in the morning and once in the evening, alongside their existing antipsychotic medication.

After 6 weeks of treatment, positive psychotic symptoms (based on PANSS positive subscale) showed significant decrease for the CBD group, compared to placebo (mean change from baseline = -3.2 +/-2.60, p = 0.019). From baseline to the end of treatment, a significantly higher proportion of patients in the CBD group was also rated by clinicians as “improved” on the CGI-I scale (treatment difference = -0.5, 95% Confidence Interval: -0.8 to -0.1, p = 0.018) and not as “severely unwell” on the CGI-S scale (treatment difference = -0.3, 95% Confidence Interval: -0.5 to 0.0, p = 0.0444), as compared to the placebo group. Although falling short of statistical significance, the CBD group also demonstrated greater improvement in cognitive performance and overall functioning.

As the first placebo-controlled trial of CBD in schizophrenia, results of the study suggest a beneficial effect of CBD as an adjunctive treatment to antipsychotic medication. Data showed that 6 weeks of CBD produced significant reductions in positive psychotic symptoms as well as improvements in illness severity, according to clinical impressions. Because CBD appears to operate independently of the dopamine pathways which conventional antipsychotics target 7, it may represent a new class of treatment for schizophrenia. Further studies are needed to explore the mechanisms underlying CBD’s therapeutic effects.

Source: McGuire P, Robson, Cubala WJ, et al. Cannabidiol (CBD) as an adjunctive therapy in schizophrenia: a multicenter randomized controlled trial. Am J Psychiatry. 2018;175(3): 225-231. DOI: 0.1176/appi.ajp.2017.17030325.

Copyright © American Psychiatric Association. All rights reserved.

 Posted May 15, 2018.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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