Cannabis has potential to unlock new cognitive treatment for schizophrenia

IHMRI researchers have discovered that an active compound in cannabis plants may alleviate cognitive impairment, providing a vital opportunity in the treatment of schizophrenia

The compound, Cannabidiol (CBD), can influence learning, memory and attention, offering potential solutions to several core symptoms of schizophrenia that can be a challenge to alleviate with existing medicines, such as cognitive impairment.

The researchers hope to use this knowledge to develop new and improved medications for schizophrenia—a debilitating mental illness that ranks among the top 10 causes of disability in developed countries worldwide.

Although current antipsychotic medications are effective against the delusions and hallucinations of schizophrenia, they are less effective in treating the cognitive and negative symptoms, such as social withdrawal and blunted emotional expression. Current medications can also have negative side effects, such as weight gain and movement disorder.

PhD candidate Ashleigh Osborne and her supervisors, Dr Katrina Green and Professor Nadia Solowij from the University of Wollongong (UOW), initially uncovered the fascinating insights about the therapeutic potential of CBD during a detailed review of 27 existing studies.

“From this review, we found that CBD will not improve learning and memory in healthy brains, but may improve aspects of learning and memory in illnesses associated with cognitive impairment, including Alzheimer’s disease, as well as neurological and neuro-inflammatory disorders,” project leader, Dr Katrina Green said. “Evidence suggests that CBD is neuroprotective and can reduce cognitive impairment associated with use of delta-9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis.”

This evidence inspired Ms Osborne to investigate whether CBD can improve cognitive impairment in a rodent model of schizophrenia, together with her supervisors and research team members, Senior Professor Xu-Feng Huang and PhD candidate Ilijana Babic.

“We found that CBD was able to restore recognition and working memory, as well as social behaviour to normal levels,” Ms Osborne said.

“These findings are interesting because they suggest that CBD may be able to treat some of the symptoms of schizophrenia that are seemingly resistant to existing medications. In addition, CBD treatment did not alter body weight or food intake, which are common side effects of antipsychotic drug treatment.”

Dr Green said the team was excited about the results but further testing was needed to determine whether CBD has the same beneficial effects in people with schizophrenia. They are now examining changes in neurotransmitter signalling pathways in the brain that result from CBD treatment in order to uncover the underlying therapeutic mechanisms.

The study review was published in the high impact journal, Neuroscience and Biobehavioral Reviews (Osborne et al, Jan 2017. 72:310-324, while the experimental findings were recently published in Nature journal, Neuropsychopharmacology, (Osborne et al

These studies were supported by the National Health and Medical Research Council (Project Grant 1007593 to Professor Nadia Solowij), the Australian Research Council (Future Fellowship FT110100752 to Professor Nadia Solowij) and a Faculty of Science, Medicine and Health Advancement Grant (2015/SPGA-S/02 to Dr Katrina Green and Distinguished Professor Xu-Feng Huang). Ashleigh Osborne is supported by an Australian Government Research Training Program Scholarship.

Please note: The researchers do not endorse the use of cannabis products to treat schizophrenia, as some ingredients, such as THC, have the potential to aggravate symptoms. This research examined one isolated compound of the cannabis plant within controlled laboratory settings. People diagnosed with a mental illness should always consult their medical practitioners about any issues with their current medication.

Top picture: Distinguished Professor Xu-Feng Huang, Professor Nadia Solowij, Dr Katrina Green and Ashleigh Osborne. 
Photo by Simon Bullard.

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