Whilst previous studies have found cannabis use to be associated with an increased risk of schizophrenia, recent research suggests that an active compound in cannabis may have some merit in treating the disorder
Researchers at Illawarra Health and Medical Research Institute (IHMRI) in Australia have discovered that cannabidiol (CBD), the second most prevalent chemical in cannabis, can alleviate cognitive impairment, offering significant potential in the treatment of schizophrenia and its symptoms.
Following a systematic review of the effect of cannabidiol on cognitive functions that are relevant to schizophrenia, CBD was found to positively influence learning, memory and attention, making it a potentially viable tool in the treatment of several core symptoms of schizophrenia, such as cognitive impairment and blunted emotional expression – symptoms which can be a challenge to mitigate with traditional medicines.
An experiment was then conducted to investigate whether CBD can improve cognitive impairment in a rodent model of schizophrenia, with the results presenting “interesting implications” for the potential use of CBD in treating the cognitive impairments and social withdrawal of schizophrenia.
Researchers hope that these findings will assist in the development of new and improved medications for schizophrenia.
A severe condition
An estimated one percent of the worldwide population is diagnosed with schizophrenia, with approximately 3.2 million Americans currently living with the disorder. In fact, it ranks among the top 10 causes of disability in developed countries worldwide. The severity of the condition also makes it a leading cause for suicide attempts, with up to half of all schizophrenia patients attempting to take their own life at some point.
Although the antipsychotic medications that are currently used to treat schizophrenia are effective at reducing the delusions and hallucinations associated with the condition, they are less effective when it comes to treating cognitive impairment and negative social behaviours, which are common symptoms of schizophrenia. Additionally, current medications can have side effects including weight gain and movement disorder.
Looking at previous studies, researchers analyzed the therapeutic potential of CBD, including its role in improving aspects of learning and memory in illnesses associated with cognitive impairment, like Alzheimer’s disease and neurological disorders.
Upon a detailed review of 27 existing studies, research supervisor Dr Katrina Green, said the evidence suggested that CBD was “neuroprotective” and was even able to reduce the cognitive impairment associated with THC, the main psychoactive component of cannabis.
Following these findings, PhD candidate Ashleigh Osborne, along with research team members Senior Professor Xu-Feng Huang and PhD candidate Ilijana Babic, conducted a study on rats to examine the effects of chronic CBD treatments on cognition and social interaction.
The researchers used a prenatal infection model; meaning, in order to generate a psychiatric disorder, pregnant rats were infected with polyinosinic-polycytidilic acid. The male offspring were then injected with 10 milligrams per kilogram of CBD twice daily for three weeks.
The animals were put through the ‘Novel Object Recognition’ and ‘rewarded T-maze’ alternation tests to assess their recognition and working memory, while the ‘social interaction test’ assessed their sociability. Their weight and food and water intake were also measured weekly.
The results showed that CBD treatment “significantly improved recognition, working memory and social interaction” in the infected mice. CBD did not, however, affect total body weight gain, food or water intake. The researchers concluded, therefore, that chronic CBD administration was able to restore recognition and working memory, as well as social behaviour, to normal levels.
“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,” Osborne said.
“In addition, CBD treatment did not alter body weight or food intake, which are common side effects of antipsychotic drug treatment.”
Although excited about their findings, the researchers noted that, as this study was conducted on rats, further testing was required to determine whether CBD has the same beneficial effects in people with schizophrenia.
The team are now examining changes in neurotransmitter signalling pathways in the brain that result from CBD treatment in order to uncover the underlying therapeutic mechanisms.
This study highlights the often contradictory effects of cannabis. In this case, whilst CBD has been shown to mitigate and reduce cognitive impairment, other studies have pointed to cannabis’ possible causal relationship to the onset of schizophrenia. This looks to be due to the different effects of specific cannabinoids, i.e. THC and CBD.
Cannabis is a vastly complex plant and research like this exposes the imperative need for a fully regulated cannabis market, where accurate testing and labelling, along with education and guidance, will allow patients to make informed choices when it comes to the cannabis they consume, with their mental health in mind.[Featured image credit: Pixabay]