New research suggests using marijuana may not increase the chances of developing psychosis.
A four-year study that followed 170 individuals at high risk for psychosis concluded that marijuana use had no effect on the development of the disorder.
Published in the journal Schizophrenia Research, measurements of alcohol, tobacco and cannabis use were taken at the start of the study to determine their impact on future outcomes.
Interestingly, the results instead pointed to alcohol as a contributing factor.
“Results revealed that low use of alcohol, but neither cannabis use nor tobacco use at baseline, contributed to the prediction of psychosis in the clinical high risk sample,” wrote Jean Addington, PhD of the University of Calgary, the study’s lead author.
Research shows substance use is significantly higher among individuals with psychosis or schizophrenia compared to the general population. As well, THC, the main active ingredient in cannabis, is known to cause temporary, psychosis-like effects in healthy users.
However, experts are still unsure whether marijuana actually contributes to the development of the disorder.
Evidence increasingly points to heritability as the underlying cause of schizophrenia. Genetics are believed to account for a large portion of the risk – as much as 80%, according to some studies.
Likewise, the latest findings are not the first to suggest a benign link between cannabis and psychosis.
A 2013 study that followed psychosis-prone adolescents over three years concluded, “the current data do not support low to moderate lifetime cannabis use to be a major contributor to psychosis or poor social and role functioning in high-risk youth.”