Cannabidiol (CBD) — a chemical compound found in — may help treat symptoms of psychosis, according to the latest findings on how CBD affects the human brain.
The results suggest that CBD could offer a treatment for the memory problems associated with psychosis, a common mental-health condition that affects 20 million people worldwide, according to the World Health Organization.
“Now not only do we know that CBD works as an antipsychotic, we know it targets the areas of the brain that need to be targeted. This really gives us confidence, and it gives us scientific justification for large scale clinical trials," lead researcher on the study Sagnik Bhattacharyya tells Inverse.
Scientists compared brain scan results of people with a diagnosis of psychosis and people without the disorder as they were doing a memory exercise. In the people with psychosis, the researchers found clear differences in the activity patterns in their prefrontal, mediotemporal, and striatal areas of the brain — those that regulate decision making, learning and memory. But when these participants were given a single dose of CBD, their brain activity patterns were more similar to those of people without the disorder.
The results provide insight into which part of the brain is affected by CBD and suggest CBD may curb symptoms of psychosis in the human brain.
The study was published Wednesday in Psychological Medicine.
CBD and brain activity
The study included a group of 13 people with a diagnosis of psychosis and 16 people without the disorder. The participants were asked to perform three different verbal-association memory tasks (such as deciding whether words were paired in a logical way, and recalling which words they’d previously seen paired, or what font they were in) while in an fMRI machine.
Those with psychosis were already on standard antipsychotic treatment at the start of the study, and they continued on the treatment throughout the study. After taking scans of their brains to establish baseline activity, the researchers then gave each participant a placebo drug and then 600 mg of CBD, and rescanned their brains.
The single dose of CBD appeared to diminish the differences in activity in the brains with psychosis and those without. For example, during memory exercises like recalling something verbally, a brain affected by psychosis has abnormal activity such as greater connectivity in the front of the brain (prefrontal, mediotemporal and striatal areas), which makes it harder to recall things logically. But after taking even just a single dose of CBD activation in these areas tended to look similar to that of a person without the condition.
The results build on a 2018 study from the same team suggesting that CBD can normalize brain activity in people with symptoms of psychosis. This new study takes the work forward by including people with a clear diagnosis.
Can CBD treat psychosis?
These results add to a growing body of research into the ways CBD may offer a treatment for different psychiatric conditions. The need is great: Current gold-standard treatments tend to work only in a subset of people and can have serious side effects when taken over the long term. CBD may be easier for the body to process, making it a more tolerable long-term option for people with chronic mental health conditions, Bhattacharyya says.
“This study is essentially showing how CBD might work, and which effects might underlie symptoms of psychosis,” he says. “But we seldom treat psychosis giving single doses; we have to give doses for various weeks before seeing clinical, meaningful results.”
Ultimately, the study sample is too small to draw definite conclusions on CBD as a treatment for psychosis patients as a group. The study also doesn't look at how brain activity changes matched up to behavior in the participants with psychosis — which means we can't know if CBD improved their performance on the memory tasks.
Bhattacharyya says his team is looking into further research on CBD treatment for psychosis with larger samples and longer time frames. The team also hopes to explore CBD as a potential treatment in other disorders with similar symptoms, like Parkinson's or dementia.
Abstract: Recent evidence suggests that cannabidiol (CBD), a non-intoxicating ingredient present in cannabis extract, has an antipsychotic effect in people with established psychosis. However, the effect of CBD on the neurocognitive mechanisms underlying psychosis is unknown. Patients with established psychosis on standard antipsychotic treatment were studied on separate days at least one week apart, to investigate the effects of a single dose of orally administered CBD (600 mg) compared to a matched placebo (PLB), using a double-blind, randomized, PLB-controlled, repeated-measures, within-subject cross-over design. Three hours after taking the study drug participants were scanned using a block design functional magnetic resonance imaging (fMRI) paradigm, while performing a verbal paired associate learning task. Fifteen psychosis patients completed both study days, 13 completed both scanning sessions. Nineteen healthy controls (HC) were also scanned using the same fMRI paradigm under identical conditions, but without any drug administration. Effects of CBD on brain activation measured using the blood oxygen level-dependent hemodynamic response fMRI signal were studied in the mediotemporal, prefrontal, and striatal regions of interest. Compared to HC, psychosis patients under PLB had altered prefrontal activation during verbal encoding, as well as altered mediotemporal and prefrontal activation and greater mediotemporal-striatal functional connectivity during verbal recall. CBD attenuated dysfunction in these regions such that activation under its influence was intermediate between the PLB condition and HC. CBD also attenuated hippocampal-striatal functional connectivity and caused trend-level symptom reduction in psychosis patients. This suggests that normalization of mediotemporal and prefrontal dysfunction and mediotemporal-striatal functional connectivity may underlie the antipsychotic effects of CBD.