Neurologist Holly Elser, MD, PhD; and Keith Humphreys, PhD; Mathew V. Kiang, ScD; Swapnil Mehta, MD; Jong H. Yoon, MD; William O. Faustman, PhD; at the Department of Neurology, Hospital of the University of Pennsylvania, have debunked prohibitionist propositions familiar to many readers here at Drug WarRant which implied that smoking marijuana leads to or causes schizophrenia:
Question: Is state cannabis legalization or commercialization associated with increased rates of psychosis-related health care claims?
Exposure: State cannabis legalization policies were measured for each state and month based on law type (medical or recreational) and degree of commercialization (presence or absence of retail outlets). […]
Main Outcomes and Measures: Outcomes were rates of psychosis-related diagnoses and prescribed antipsychotics. […]
Conclusions and Relevance: 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. […]
Findings: In this cohort study of claims data from 63,680,589 beneficiaries from 2003 to 2017, there was no statistically significant difference in the rates of psychosis-related diagnoses or prescribed antipsychotics in states with medical or recreational cannabis policies compared with states with no such policy. […]
Meaning: The findings of this study do not support an association between state policies legalizing cannabis and psychosis-related outcomes […]