New research indicates that there is no significant relationship between rates of psychosis-related health outcomes and countries with medical and recreational cannabis policies, according to findings published in JAMA Network is open.
However, exploratory secondary analyzes noted higher rates of diagnoses of psychosis-related illnesses in states with recreational cannabis policies. The main subgroups diagnosed included men, individuals 55-64 years of age, and Asian recipients.
“Results from the fully adjusted models showed that, compared with no legalization policy, countries with legalization policies experienced no statistically significant increase in rates of psychosis-related diagnoses…or antipsychotic prescriptions,” the study authors wrote.
There are 38 states that now allow the use of medical cannabis and nearly half of those states also allow recreational use. Since 2019, at least 48.2 million US citizens ages 12 and older are believed to have used cannabis; However, controversy surrounds its effect on psychotic disorders, which can dampen important societal functions such as education and the maintenance of employment.
Investigators have previously linked heavy cannabis use to a three-fold increased risk of schizophrenia compared to non-users and an increased risk of self-harm, especially in men younger than 40.
The authors of the current study conducted a retrospective analysis examining the relationship between government cannabis legalization and rates of healthcare claims related to psychosis in privately insured individuals. They hypothesized that states with legalized entertainment and marketing policies would have more patients with psychosis-related illnesses and antipsychotic prescriptions.
Using the Optum Clinformatics Data Mart database, researchers evaluated 63,680,589 beneficiaries and their insurance claims, looking at the relationship between antipsychotic claims and states that legalized cannabis.
The team noted that there was no significant increase in the rate of people diagnosed with a psychosis-related illness in states with policies that legalize cannabis, whether for medical or recreational use. Nor did they see a significant increase in antipsychotic prescriptions.
Subgroup analysis provided insights into cannabis use and psychosis-related prognosis across different genders, ages, races, and ethnicities. This was an important predictor of mental health care, as more men between the ages of 55 and 64 were observed to use services than younger adults and older adults. Race and ethnicity were often not reported, setting the stage for future studies, according to the investigators.
Study limitations included that the results may not be generalizable to uninsured patients, and there may be confounding variables, such as transfers of psychotic patients to states that legalize cannabis. In addition, no adjustments were made for multiple comparisons in prospective analyses, and the study included a small sample size.
“As states continue to introduce cannabis policies, the implications of state legalization of cannabis for psychotic disorders warrant further 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 legalization of cannabis and health care use associated with psychosis. January 25, 2023. GammaNet is open. 2023; 6 (1): e2252689. doi: 10.1001/jamanetworkopen.2022.52689.001