Cannabis derivative on trial to reduce psychotic symptoms in schizophrenia

A new study led by Queensland Centre for Mental Health Research (QCMHR) researchers, is putting a cannabis derivative to the test to improve outcomes for people with a treatment-resistant form of schizophrenia.

The trial will see whether cannabidiol, an active component of cannabis, is effective for reducing psychotic symptoms in patients with clozapine refractory schizophrenia when used alongside the standard treatment regime.

QCMHR Professor Dan Siskind, is leading the study out of Brisbane’s Princess Alexandra Hospital, where he works as a psychiatrist.

He said that people with treatment refractory schizophrenia have few options to reduce psychotic symptoms when clozapine, the standard drug for treatment, is not effective.

“Approximately 33 per cent of people with schizophrenia are treatment refractory, and 40 per cent of these do not respond to clozapine, which is currently the gold standard treatment we have available,” Professor Siskind said.

“Our world leading randomised control trial hopes to offer new hope for people with treatment refractory schizophrenia, by offering a new treatment option.

“People who are on clozapine – our most effective antipsychotic – are still getting symptoms and desperately need some extra support.

“Cannabidiol is a safe compound, known to reduce anxiety and we think it may also have an antipsychotic effect that offers real promise to patients with treatment refractory schizophrenia.

“Cannabidiol is different to THC, which is the other main psychoactive cannabis compound – THC is the compound that may make users feel “high”, and is associated with psychosis – we will remove all THC from the cannabidiol used in our study.

“This trial will provide us with robust evidence to see if these antipsychotic benefits are evident for our patients who are already on clozapine.”

Approximately 1 in every 100 people has schizophrenia, so the need to find alternative treatments for people who have treatment refractory schizophrenia remains high, with symptoms including auditory hallucinations, paranoia, lack of motivation, and issues with cognition.

The randomised control trial will build on results found in schizophrenia studies conducted overseas.

“A UK study of people with schizophrenia and ongoing psychotic symptoms, but who were not necessarily on clozapine, experienced reduced psychotic symptoms with cannabidiol,” Professor Siskind said.

The study team includes Dr Nicola Warren, Associate Professor Shuichi Suetani, Professor Steve Kisely, Dr Victoria De Monte, Professor Iain Macgregor and, Ms Manju Shine and is funded by the PA Research Foundation, Metro South Health Research Support Scheme and The Lambert Initiative at the University of Sydney.

QCMHR is a research partnership between Queensland Health and The University of Queensland via the School of Public Health and Queensland Brain Institute. Hosted by West Moreton Health, QCMHR is funded to work state-wide in Queensland and contribute to the Australian and global research effort to improve mental health.

Media Contact: Kate Gadenne, Research Development Manager, 0438 727 895

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