Summary: According to researchers, Cannabidiol, an active compound in cannabis plants, could help to alleviate cognitive impairment in people with 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.
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.
Funding: 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 Senior Professor Xu-Feng Huang). Ashleigh Osborne is supported by an Australian Government Research Training Program Scholarship.
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Original Research: Abstract for “A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia” by Ashleigh L. Osborne, Nadia Solowij, and Katrina Weston-Green in Neuroscience and Biobehavioral Reviews. Published online January 2017 doi:10.1016/j.neubiorev.2016.11.012
Abstract for “Improved Social Interaction, Recognition and Working Memory with Cannabidiol Treatment in a Prenatal Infection (poly I:C) Rat Model” by Ashleigh L Osborne, Nadia Solowij, Ilijana Babic, Xu-Feng Huang & Katrina Weston-Green in Neuropsychopharmacology. Published online February 27 2017 doi:10.1038/npp.2017.40
A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia
Background and objectives
Cognitive impairment is a core symptom domain of schizophrenia, neurological disorders and substance abuse. It is characterised by deficits in learning, memory, attention and executive functioning and can severely impact daily living. Antipsychotic drugs prescribed to treat schizophrenia provide limited cognitive benefits and novel therapeutic targets are required. Cannabidiol (CBD), a component of the cannabis plant, has anti-inflammatory and antipsychotic-like properties; however, its ability to improve cognitive impairment has not been thoroughly explored. The aim of this systematic review was to evaluate preclinical and clinical literature on the effects of CBD in cognitive domains relevant to schizophrenia.
A systematic literature search was performed across numerous electronic databases for English language articles (January 1990–March 2016), with 27 articles (18 preclinical and 9 clinical studies) included in the present review.
CBD improves cognition in multiple preclinical models of cognitive impairment, including models of neuropsychiatric (schizophrenia), neurodegenerative (Alzheimer’s disease), neuro-inflammatory (meningitis, sepsis and cerebral malaria) and neurological disorders (hepatic encephalopathy and brain ischemia). To date, there is one clinical investigation into the effects of CBD on cognition in schizophrenia patients, with negative results for the Stroop test. CBD attenuates Δ9-THC-induced cognitive deficits.
The efficacy of CBD to improve cognition in schizophrenia cannot be elucidated due to lack of clinical evidence; however, given the ability of CBD to restore cognition in multiple studies of impairment, further investigation into its efficacy in schizophrenia is warranted. Potential mechanisms underlying the efficacy of CBD to improve cognition are discussed.
“A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia” by Ashleigh L. Osborne, Nadia Solowij, and Katrina Weston-Green in Neuroscience and Biobehavioral Reviews. Published online January 2017 doi:10.1016/j.neubiorev.2016.11.012
Improved Social Interaction, Recognition and Working Memory with Cannabidiol Treatment in a Prenatal Infection (poly I:C) Rat Model
Neuropsychiatric disorders such as schizophrenia are associated with cognitive impairment, including learning, memory and attention deficits. Antipsychotic drugs are limited in their efficacy to improve cognition; therefore, new therapeutic agents are required. Cannabidiol (CBD), the non-intoxicating component of cannabis, has anti-inflammatory, neuroprotective and antipsychotic-like properties; however, its ability to improve the cognitive deficits of schizophrenia remains unclear. Using a prenatal infection model, we examined the effect of chronic CBD treatment on cognition and social interaction. Time-mated pregnant Sprague-Dawley rats (n=16) were administered polyinosinic-polycytidilic acid (poly I:C) (POLY; 4 mg/kg) or saline (CONT) at gestation day 15. Male offspring (PN56) were injected twice daily with 10 mg/kg CBD (CONT+CBD, POLY+CBD; n=12 per group) or vehicle (VEH; CONT+VEH, POLY+VEH; n=12 per group) for 3 weeks. Body weight, food and water intake was measured weekly. The Novel Object Recognition and rewarded T-maze alternation tests assessed recognition and working memory, respectively, and the social interaction test assessed sociability. POLY+VEH offspring exhibited impaired recognition and working memory, and reduced social interaction compared to CONT+VEH offspring (p<0.01). CBD treatment significantly improved recognition, working memory and social interaction deficits in the poly I:C model (p<0.01 vs POLY+VEH), did not affect total body weight gain, food or water intake, and had no effect in control animals (all p>0.05). In conclusion, chronic CBD administration can attenuate the social interaction and cognitive deficits induced by prenatal poly I:C infection. These novel findings present interesting implications for potential use of CBD in treating the cognitive deficits and social withdrawal of schizophrenia.
“Improved Social Interaction, Recognition and Working Memory with Cannabidiol Treatment in a Prenatal Infection (poly I:C) Rat Model” by Ashleigh L Osborne, Nadia Solowij, Ilijana Babic, Xu-Feng Huang & Katrina Weston-Green in Neuropsychopharmacology. Published online February 27 2017 doi:10.1038/npp.2017.40