A new study published this month in Jama Network Open shows no links to an increase in psychosis-related conditions or incidents in states that have legalized cannabis for adult or medical use.
Researchers used the Optum Clinformatics Data Mart Database, which contains commercial and Medicare Advantage claims of more than 63 million unique individuals followed between January 1, 2003, and December 31, 2017. All beneficiaries aged 16-and-older with at least one month of insurance eligibility during the period were included in the study.
The study used a panel fixed-effects design. The state-month was the unit used to analyze the association of state cannabis policies with the rate of psychosis-related healthcare claims. The study authors used the number of unique claims with psychosis-related diagnoses, prescribed, antipsychotics, and enrolled individuals for each state-month of follow-up and merged the data with time-varying categorical measures of state cannabis policy level and state-level demographic, economic, and social characteristics.
The researchers found more than 7 million psychosis-related diagnoses and recorded more than 20 million filled prescriptions for antipsychotic drugs over the study period. And, during the research period, medical or adult-use cannabis reforms were approved in 29 states.
“In this retrospective cohort study of commercial and Medicare Advantage claims data, state medical and recreational cannabis policies were not associated with a statistically significant increase in rates of psychosis-related health outcomes.” — “State Cannabis Legalization and Psychosis – Related Health Care Utilization
In their secondary analysis, researchers did find that rates of psychosis-related diagnoses increased slightly among men during the study period, particularly those aged 55 to 64 years and those who were Asian, in states that permit adult cannabis use compared with states that do not.
“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,” the authors write.
The study was conducted by researchers at the University of Philadelphia, Stanford University, and Veterans Affairs Palo Alto Health Care System.
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