Medical Research

Cannabidiol Trial for the Treatment of Schizophrenia

Written by Derek Johnson

Schizophrenia is a psychiatric disorder that affects the brain and body. Those afflicted with the condition experience distortions in thinking and perceptions of the world around them. It also can impact their actions, judgment, and language. Hallucinations, both auditory and visual, are common.

Over 20 million people around the world have this chronic disorder. Patients often die earlier than those without schizophrenia due to comorbid conditions like cardiovascular disease, and are discriminated against regularly by society, as the disease carries a terrible stigma.

Fortunately, treatment is available through therapy and medications. However, these medications bring with them many undesirable side effects, such as blurred vision, dry mouth, tremors, drowsiness, restlessness, and weight gain.

While studies have pursued the role of the endocannabinoid system in schizophrenia, a well-documented link (correlational not causal) between cannabis and psychosis has made some weary about using cannabinoids to treat this condition. However, this relationship remains controversial, as there is some evidence that patients early on in their disease before diagnosis may actually be using cannabis to treat their symptoms, rather than early cannabis use leading to the development of later psychosis.

Of course the way to thoroughly evaluate any new treatment, including cannabinoids, involves clinical trial testing. So let’s take a close look at the results of such study.

Researchers conducted a Phase 2 double-blind, randomized trial where 43 patients were given an oral solution of CBD (1000 mg per day) and 45 were given a placebo (inactive substance) along with the antipsychotic medicine they were already taking.[1]

Patients were evaluated using standard scales of symptom measurement, including the Positive and Negative Syndrome Scale, Scale for the Assessment of Negative Symptoms, Clinical Global Impressions Scale, the Global Assessment of Functioning, and Brief Assessment of Cognition in Schizophrenia.

After six weeks, researchers found that patients treated with CBD experienced fewer psychotic symptoms like delusions and hallucinations. They were also more frequently given the designation of clinical improvement.[1]

Additionally, participants who took CBD demonstrated greater improvements in cognitive performance and overall functioning over those who took placebo. While these results were not statistically significant, they are certainly promising, as these symptoms are not addressed by available medications.

Overall, the CBD group tolerated the cannabinoid well and had similar rates of adverse effects as the placebo group.

More research is clearly needed to better understand both the link between cannabis and schizophrenia and the potential of CBD specifically as an adjunctive treatment. But as always, be sure to speak with your doctor before starting on cannabinoids to treat any conditions.

Image Credit: Karolina Grabowska

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1. McGuire, P, et al. Cannabidiol (CBD) as an adjunctive therapy in schizophrenia: A multicenter randomized controlled trial. American Journal of Psychiatry. 2018; 175(3):225-231.


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Derek Johnson

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