Psychosis, a severe mental disorder characterized by a loss of grip on reality, can include unsettling hallucinations and delusions. As no one’s been able to pin down a single cause of psychosis, it’s been even harder to pin down a treatment. But researchers behind a new JAMA Psychiatry study seem to be on the right track. In the study, they report that they’ve found a way to reset the psychosis-afflicted brain using an unlikely plant: marijuana.

Researchers are increasingly finding evidence that the active components of marijuana can help ease symptoms in people with epileptic seizures, chronic pain, and post-traumatic stress disorder, but there’s much to be learned about its relationship to psychosis. The most well-known cannabinoid Δ⁹-tetrahydrocannabinol — better known as THC — has previously been linked to the development of psychosis in some people. But in the new study, the authors report that another cannabinoid called cannabidiol — CBD — can actually help treat it.

Cannabidiol (CBD), another compound found in cannabis, appears to "reset" the brains of people at high risk of psychosis, at high doses. Pixabay

In the paper, a team of UK researchers showed that a single dose of CBD can normalize brain activity associated with psychosis. Psychosis is associated with distinctive patterns of brain activation as detected by MRI in the striatum, medial temporal lobe, and midbrain. In a double-blind study of 33 people at high risk of psychosis and 19 healthy controls, the study’s authors found that patients at high risk of psychosis had abnormally elevated activity in these regions compared to the control subjects. But one large dose of CBD — 600 milligrams — quickly and significantly reduced the brain activity in those brain regions down to normal levels.

“We were pleasantly surprised and particularly impressed with the fact that even a single dose of cannabidiol had an effect on brain regions implicated in psychosis in a manner suggesting cannabidiol can help re-adjust brain activity to normal levels, consistent with its role as an antipsychotic,” Sagnik Bhattacharyya, M.D., Ph.D., a professor of translational neuroscience and psychiatry at King’s College London and the study’s first author, tells Inverse. “We know from earlier studies in patients with psychosis that Cannabidiol has antipsychotic effects. However, how cannabidiol might work to treat psychosis, i.e. its mechanisms have not been clear until now.”

Researchers found that CBD decreased activity in the caudate (red/yellow), a part of the midbrain associated with a clinical risk of psychosis. King's College London

As Bhattacharyya suggests, this latest study is not the first to show the therapeutic benefit of CBD. Several of the researchers who produced this paper also published a study in December 2017 showing that patients treated with CBD reported lessened psychotic symptoms and were less likely to be rated as psychotic by their psychiatrists.

That study raised the big question of just how CBD works, and this latest one seems to have shed light on that issue. Though the subjects in this study had not actually been diagnosed with psychosis, they exhibited distressing symptoms suggesting a clinical high risk for developing psychosis. The fact that CBD reset or normalized their brain activity to typical levels suggests that the researchers are onto something.

CBD, notably, has a low potential for abuse because it doesn’t get people high.

The study’s authors’ next step is to launch a clinical trial into CBD’s effect on psychosis — a study for which they’ve already secured funding as a result of this latest paper. “If successful, the new trial will provide definitive proof of cannabidiol’s efficacy as an antipsychotic treatment and pave the way for its use in the clinic,” Bhattacharyya says. “One of the main advantages of cannabidiol is that it is safe and seems to be very well tolerated, making it in some ways an ideal treatment.”

Editor’s Note: As of 9:45 A.M. Eastern, 8/30/2018, this story has been updated to include original comments from the study’s first author Sagnik Bhattacharyya.