This is the largest known study to consider medical and recreational cannabis policies with US psychosis-related health care claims.
New research indicates that there is not a statistically significant association between rates of psychosis-related health outcomes and states that have medical and recreational cannabis polices, according to findings published in JAMA Network Open.
However, exploratory secondary analyses did observe higher rates of diagnosis for psychosis-related illness in states with recreational cannabis policies. The main subgroups who were diagnosed included men, individuals aged 55 to 64 years, and Asian beneficiaries.
“Results from fully-adjusted models showed that, compared with no legalization policy, states with legalization policies experienced no statistically significant increase in rates of psychosis-related diagnoses…or prescribed antipsychotics,” the study authors wrote.
There are 38 states that now permit medical cannabis use and nearly half of these states also permit recreational use. Since 2019, at least 48.2 million US citizens aged 12 years and older are believed to have used cannabis; however, controversy surrounds its effect on psychotic disorders, which can inhibit important societal functions such as education and employment maintenance.
Investigators previously linked heavy use of cannabis with the tripling of the risk for developing schizophrenia compared to non-users and increasing the risk of self-harm, especially in men under 40 years of age.
The authors of the current study conducted a retrospective analysis to examine an association between state cannabis legalization and rates of psychosis-related health care claims in privately insured individuals. They hypothesized that states with legal recreational and commercialization policies would have a higher number of patients with psychosis-related illness and antipsychotic prescriptions.
Using the Optum Clinformatics Data Mart Database, researchers evaluated 63,680,589 beneficiaries and their insurance claims, looking at the association between claims for antipsychotics and states that have legalized cannabis.
The team observed no significant increase in the rate of people diagnosed with a psychosis-related illness in states with policies that legalize cannabis, be it for medical or recreational use. They also did not observe a significant increase in prescriptions for antipsychotics.
A subgroup analysis provided insight about the use of cannabis and psychosis-related diagnosis among different sexes, ages, races, and ethnicities. This served as a significant predictor of mental health care, with men aged 55 to 64 years observed to use services more than younger and older adults. Race and ethnicity were not reported as often, paving the way for future studies, according to the investigators.
Study limitations included that the findings may not be generalizable to uninsured patients, and there may be confounding variables, such as the relocation of psychosis patients to states that legalize cannabis. Additionally, no adjustments were made for multiple comparisons in future analyses, and the study included a small sample size.
“As states continue to introduce cannabis policies, the implications of state cannabis legalization for psychotic disorders warrants continued study, particularly in data settings where direct measures of disease onset and severity are available,” the study authors wrote.
Elser H, Humphreys K, Kiang M, et al. State Cannabis Legalization and Psychosis-Related Health Care Utilization. January 25, 2023. JAMA Netw Open. 2023;6(1):e2252689. doi:10.1001/jamanetworkopen.2022.52689