A new study published this month in Jama Network Open shows no increase in psychosis-related disorders or incidents in US states that have legalized cannabis for adult or medical use.
The researchers used the database Optum Clinformatics Data Martwhich contains insurance data for more than 63 million unique individuals tracked between January 1, 2003 and December 31, 2017. All beneficiaries ages 16 and older with at least one month of insurance eligibility during the period were included in the study.
The study authors used the number of unique claims with psychosis-related diagnoses, antipsychotics prescribed, and enrollees for each month of follow-up and merged the data with time-varying categorical measures of level state cannabis policy; and demographic, economic, and social characteristics of the state.
The researchers found more than 7 million psychosis-related diagnoses and recorded more than 20 million prescriptions filled for antipsychotic drugs during 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 claims and Medicare Advantage data, state medical and recreational cannabis policies were not associated with a statistically significant increase in rates of psychosis-related health outcomes.” in the study.
In their secondary analysis, the researchers found that rates of psychosis-related diagnoses increased slightly among men over the study period, particularly among those aged 55 to 64 and among Asians, States that allow cannabis use by adults, versus states that do not.
“The results of the fully fitted models showed that, compared to no legalization policy, states with legalization policies did not experience a statistically significant increase in rates of psychosis-related diagnoses,” write authors.
The study was conducted by researchers from the University of Philadelphia, Stanford University and the Veterans Affairs Palo Alto Health Care System.