There is mounting evidence suggesting that frequent, heavy use of marijuana can increase the chances of developing a psychotic disorder, particularly for individuals who are already genetically predisposed to psychosis. Research released in October 2021 in the American Journal of Psychiatry shows that users of marijuana were more likely to have self-reported psychosis than those who did not use marijuana.
Study details
This latest study examining the relationship between cannabis use and psychosis utilized data from the National Epidemiologic Survey on Alcohol and Related Conditions, which collects data on drug use and self-reported psychosis. The authors compared results from the 2001-2002 and 2012-2013 versions of the surveys and used logistic regression to determine if the relationship between cannabis use and psychosis was significant and whether this relationship changed over time.
Results
Before examining the cannabis factor, the authors also investigated the overall prevalence of self-reported psychotic disorders among adults over time, finding a significant increase, from a prevalence of 0.33% in 2002 to 0.80% in 2013, a percentage increase of 142%. While self-reported measures cannot be seen as definitive indicators, this result indicates that rates of psychosis are increasing in the US and furthers the need for more investigation into the accurate measure of prevalence of severe mental illness in the country.
In both time periods of the surveys, the authors found that the prevalence of self-reported psychotic disorders was significantly greater for adults who used cannabis than those who did not. In 2013, the rate of self-reported psychosis was 1.89% for those who used marijuana and 0.68% for those who did not.
Interestingly, for those adults who met the DSM-IV definition of cannabis dependence there was no association between this factor and self-reported psychosis in the 2002 survey, but there was a significant association between cannabis dependence and psychotic disorders in the 2013 survey group. Additionally, they found that those who met the threshold for cannabis dependence were at an increased risk of having a psychotic disorder than those who used cannabis but did not meet the dependence threshold.
The authors found no associations for those who lived in a state with a medical cannabis law and those who did not for prevalence of self-reported psychosis.
Implications
The authors note the importance of their first finding in the study – that self-reported rates of psychosis have significantly increased over time in the United States. They highlight that their study is the first to report this increase using large-scale, nationally representative samples of U.S. adults. Treatment Advocacy Center has long called for an increased emphasis on measuring the rates of severe mental illness and these results further indicate a need for understanding the prevalence of mental illness in this country.
Their findings on the association of cannabis use and self-reported psychosis adds to the growing literature that suggests there is a relationship between marijuana use and psychotic disorders. The authors note that these findings are useful for physicians and clinicians to know which of their patients may be more likely to be at risk for developing a psychotic disorder. It is also important information for individuals who might already be at risk for a psychotic disorder due to family history, indicating that marijuana could potentially increase this risk for developing a psychotic disorder.
References
