Could a cannabis extract be used as an antipsychotic?
Scientists have unravelled how a non-intoxicating component of cannabis acts in key brain areas to reduce abnormal activity in patients at risk of psychosis.
The finding suggests the ingredient could become a novel antipsychotic medicine.
While regular use of potent forms of cannabis can increase the chances of developing psychosis, the chemical cannabidiol appears to have the opposite effect.
Cannabidiol is the same cannabis compound that has also shown benefits in epilepsy, which is currently being trialled in children under a scheme funded by the NSW Government.
Previous research at King's College London, UK has shown that cannabidiol may counter the effects of tetrahydrocannabinol or THC, the substance in cannabis that makes people high.
But how this happened had been a mystery until now.
Scanning the brains of 33 young people who were experiencing distressing psychotic symptoms but had not been diagnosed with full-blown psychosis, Dr Sagnik Bhattacharyya and colleagues found that cannabidiol capsules reduced abnormal activity in the striatum, medial temporal cortex and midbrain.
Abnormalities in all three of these brain regions have been linked to the onset of psychotic disorders such as schizophrenia, the researchers note in JAMA Psychiatry.
Most current antipsychotic drugs target the dopamine chemical signaling system in the brain, while cannabidiol works in a different way.
Significantly, the compound is very well tolerated, avoiding the adverse side effects such as weight gain and other metabolic problems associated with existing medicines.
"One of the reasons cannabidiol is exciting is because it is very well tolerated compared to the other anti-psychotics we have available," Dr Bhattacharyya said.
"There is an urgent need for a safe treatment for young people at risk of psychosis."
The Institute of Psychiatry, Psychology and Neuroscience at King's College now plans a large 300-patient clinical trial to test the true potential of CBD as a treatment.
Recruitment into the trial is expected to start in early 2019.