Weed use has long been associated with the ability to sometimes induce psychotic episodes. In people at risk for such mental disorders, psychoactive marijuana strands may bring on paranoia and other psychoses, according to a November 2017 study published in Psychiatry Research. Adolescent use of psychoactive marijuana is also linked to schizophrenia, according to a July 2017 study published in Human Molecular Genetics.

But there's one key detail that people who don't smoke often miss when labeling marijuana this way: These psychoactive effects are associated with THC (tetrahydrocannabinol), the psychoactive compound in weed. A different chemical compound, CBD (cannabidiol), has been found to do the opposite: CBD reduces symptoms of mental issues in those already diagnosed with psychosis, according to a new study published in the American Journal of Psychiatry.

Researchers at King’s College London gave 83 patients with schizophrenia a dose of CBD every day for six weeks alongside their regular antipsychotic medicine. The researchers found that patients who received CBD had significantly reduced symptoms and improvements in their health; the patients' personal psychiatrists rated them as having improved overall.

This was the first placebo-controlled trial using CBD to treat psychosis. The authors noted in the conclusion that: “These findings suggest that CBD has beneficial effects in patients with schizophrenia. As CBD’s effects do not appear to depend on dopamine receptor antagonism, this agent may represent a new class of treatment for the disorder.”