Could one of the key active components in cannabis, when used alongside an existing medication, be a solution for schizophrenia patients, who are not responding to traditional treatments? A new study co-funded by the PA Research Foundation is hoping to find out.
As many as 33 per cent of people with schizophrenia have what is known as treatment refractory schizophrenia, meaning they are not responding to first line antipsychotic treatments such as aripiprazole and risperidone.
Around 40 per cent of that cohort will respond to clozapine, while 60 per cent will not. That 60 per cent have what is termed clozapine refractory schizophrenia and the project, led by PA Hospital (PAH) based Professor Dan Siskind hopes to see whether Cannabidiol when used along with clozapine can reduce the psychotic symptoms in these patients.
Prof Dan Siskind
"Cannabidiol, unlike THC has, more anxiety-reducing effects, and we think it may have an antipsychotic effect." Prof Siskind said.
"We think that if we add on cannabidiol to people with schizophrenia who are already on clozapine, it may provide some additional antipsychotic benefits.
"Cannabidiol tends have very few side effects. In fact, people who have used purified cannabidiol, which does not contain any THC, tend to report that they don't notice any change, or feel a sense of calm.
"There is a lack of other effective add-on treatments for people with schizophrenia on clozapine. We want to identify new safe and effective add-on treatments. Cannabidiol holds promise and is unlikely to cause harm."
With no cure for the 1 in 100 people with schizophrenia currently available, the need to find alternative treatments for patients who are considered clozapine refractory remains high, with symptoms including auditory hallucinations, paranoia, lack of motivation and issues with cognition.
The study entitled An RCT of Cannabidiol for Clozapine Refractory Schizophrenia (CanCloz), will be run as a randomised control trial with some patients receiving cannabidiol and others receiving a placebo and will build upon results found in schizophrenia studies conducted overseas.
"There was a large study that came out of the UK for people who had schizophrenia and ongoing psychotic symptoms, but who were not necessarily on the most effective antipsychotic, clozapine. They gave people cannabidiol or a placebo, and there was a reduction in the overall psychotic symptoms with the cannabidiol group," Professor Siskind said.
"People who are on our most effective antipsychotic, clozapine, and are still getting symptoms are the ones who desperately need some extra support."
Joined by colleagues Dr Nicola Warren, A/Prof Shuichi Suetani, Prof Steve Kisely, Dr Veronica De Monte, Prof Iain Macgregor and Manju Shine in running the study, Professor Siskind said funding from the PA Research Foundation is absolutely crucial to the success of the study.
"We are very excited to be partnering with the PA Research Foundation to do this first in the world research. It's great that this is happening, not just in Brisbane, but right here at the PA," he said.
"Our mental health group is doing some global, cutting-edge research and the support from the PA Foundation Metro South Health Research Support Scheme has been instrumental to giving us a competitive edge. We're incredibly thankful for the support provided by the PA Foundation Metro South Health Research Support Scheme.
"PA Research Foundation funds will be matched by The Lambert Initiative at the University of Sydney. The Lambert Initiative was set up to provide national and international leadership both in the science of medicinal cannabis and in the discovery and development of cannabis-based medicines."
According to Professor Siskind who is both a clinician at the PAH and an academic at UQ, the PA Research Foundation's supporters have been integral to developing the careers of researchers such as himself so that they can help more people.
"One of my first ever grants, six years ago, was a PA Research Foundation Early Career Researcher grant. With the research that came from that funding, I have been able to be successful in attracting funding from the National Health and Medical Research Council" he said.
"Because the PA Foundation invested in me as an early career researcher, it allowed me to build up a track record of clinically meaningful research that can help patients with physical health comorbidity and treatment-refractory schizophrenia. I have been able to leverage this early support to attract further competitive research funding.
"The PA Foundation's donors provision of the seed money for researchers here at the PA Hospital has greatly helped grow our research capacity and enabled us to become competitive for national grants."
"I'm incredibly thankful to the donors of the PA Research Foundation because they have really helped create the culture of bench to bedside research here on our campus."
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