The new study was conducted by scientists at King's College London (KCL) in the United Kingdom.
It was spearheaded by Sagnik Bhattacharyya, Ph.D., from KCL's Institute of Psychiatry, Psychology & Neuroscience.
Bhattacharyya explains the motivation for the recent study, saying, "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."
Cannabidiol has already been proven to have antipsychotic effects. For instance, a 6-week clinical trial has shown that it relieves psychotic symptoms when taken in conjunction with antipsychotic medication. Likewise, a 4-week trial found that the compound is just as effective as traditional antipsychotics.
However, the neurological mechanisms responsible for this effect were unknown — until now. The new research sheds light, bringing us closer to a potential cannabidiol-based treatment for psychosis.
According to recent estimates, 3.5 percent of the population of the United States has experienced symptoms of psychosis, such as visual or auditory hallucinations.
Studying cannabidiol's effects on the brain
Bhattacharyya and his colleagues examined the effects of cannabidiol on 33 study participants at "clinical high risk" of psychosis, who, although not diagnosed with the condition yet, had experienced psychotic episodes.
Of these, 16 participants took a single oral dose of 600 milligrams of cannabidiol, while 17 participants took a placebo.
The researchers compared the results in these groups with those of a control group of 19 people who had not experienced psychosis.
Using functional MRI, the researchers scanned the participants' brains as they took a memory test. The memory tasks are known to activate three brain areas typically hyperactive in psychosis: the striatum, the medial temporal cortex, and the midbrain.
Cannabidiol normalizes brain activity
In the psychosis group, the brain activity of people who took cannabidiol was less intense than that of those who received placebo. The compound brought down the activity in these brain areas to near-normal levels.
Specifically, in each of the three brain regions, "the level of activation following administration of cannabidiol [...] was intermediate between the response in healthy control individuals who did not receive any drug and in patients at clinical high risk receiving placebo."
"These results," conclude the authors, "suggest that cannabidiol may normalize dysfunction in these brain regions, which are critically implicated in psychosis, and this may underlie its therapeutic effects in psychosis."
To the authors' knowledge, this is the first study to show the effect that cannabidiol has on the brain and the neurological mechanisms by which it could help relieve psychotic symptoms.
Cannabidiol may be the 'ideal treatment'
Bhattacharyya comments on these findings, saying, "Our results have started unraveling the brain mechanisms of a new drug that works in a completely different way to traditional antipsychotics."
In the near future, he and his team plan to launch a large multicenter clinical trial of cannabidiol for treating psychosis in young people who are at risk.
"There is an urgent need for a safe treatment for young people at risk of psychosis," Bhattacharyya explains.
"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. If successful, this trial will provide definitive proof of cannabidiol's role as an antipsychotic treatment and pave the way for use in the clinic."