Research from King’s College London has found that a single dose of the cannabis extract cannabidiol can help reduce brain function abnormalities seen in people with psychosis. Results from a new MRC-funded trial, published in JAMA Psychiatry, provide the first evidence of how cannabidiol acts in the brain to reduce psychotic symptoms.
Cannabidiol, also referred to as CBD, is a non-intoxicating compound found in cannabis. A purified form of cannabidiol has recently been licensed in the USA as a treatment for rare childhood epilepsies, and a 2017 King’s College London trial has demonstrated cannabidiol has anti-psychotic properties. However, exactly how cannabidiol may work in the brain to alleviate psychosis has remained a mystery.
“The mainstay of current treatment for people with psychosis are drugs that were first discovered in the 1950s and unfortunately do not work for everyone,” says Dr. Sagnik Bhattacharyya, from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN). “Our results have started unravelling the brain mechanisms of a new drug that works in a completely different way to traditional anti-psychotics.”
Underlying Causes for CBD’s Therapeutic Effects
What are the neurocognitive mechanisms that underlie the putative therapeutic effects of cannabidiol in psychosis? In other words, does CBD really help treat psychosis? And if so, how? Such are the questions motivating a new study published in JAMA Psychiatry.
Researchers began with the premise that cannabidiol (CBD) has antipsychotic effects in humans. Exactly how it has that effect on the brain isn’t fully understood. Psychiatrists study the chemical reactions that lead to or stem from atypical mental states. For this study, researchers wanted to try to isolate the specific chemical alterations that give CBD its therapeutic and potentially antipsychotic effects.
To do so, the study examined the effects of CBD in 33 individuals at clinical high risk (CHR) of psychosis. Previous studies have identified the regions in the brain that become perturbed in individuals with psychosis and at CHR. So, the JAMA study had a hypothesis: maybe CBD attenuates, or lessens, those disturbances in the parts of the brain associated with psychosis.
Study’s Findings Confirm CBD’s Influence on Brain Regions Linked to Psychosis
The study’s 33 CHR participants were part of a double-blind randomized clinical trial with 19 healthy control individuals. Some participants received a single, 600 mg oral dose of cannabidiol; others, no CBD or a placebo. Researchers examined how the CBD affected the striatum, medial temporal cortex and midbrain—the target brain regions.
The investigation revealed that all three brain regions experienced modulated activation as a result of the CBD. Using an MRI while participants performed a verbal learning task, researchers measured brain activation alongside healthy control individuals who took no CBD, and high-risk patients who received a placebo. What they found was that CHR patients who took CBD had activation levels about in the middle between healthy individuals with no disturbances and CHR patients who took no CBD.
In short, CBD did have the attenuating effects researchers had hypothesized. The oral dose of cannabidiol helped normalize dysfunction in all three brain regions. And that means the study may have identified one of the mechanisms responsible for CBD’s therapeutic benefits.
While the study’s findings have implications for psychiatric medicine and treating individuals at high risk for psychosis, it has wider importance for anyone interested in the effects of cannabis on mental health.
There are studies that have drawn links between regular and frequent cannabis use and the development of psychosis. Others have linked psychosis with changes to the endocannabinoid system, whether cannabinoid-stimulated or not. At the same time, research shows CBD, a non-psychoactive cannabinoid, has an almost opposite neural and behavioral effect to THC. With this latest study, scientists now know more about why that is.