Impact of cannabis legalization and commercialization on substance use and mental health outcomes in psychosis

Project Summary Legalization of cannabis and subsequent expansion of commercial cannabis markets are spreading rapidly across the United States. While many can use cannabis without significant harm, individuals with serious mental illnesses such as schizophrenia and other psychotic disorders are disproportionately likely to experience harms from cannabis use, and cannabis commercialization could worsen outcomes for this vulnerable population. As an early career psychiatrist and health services researcher with specialty interests in addictions and psychosis, I am proposing to use quasi-experimental difference in difference methods to study the effects of commercialization on cannabis use and mental health outcomes among individuals with psychosis. I am first proposing to analyze the Population Assessment of Tobacco and Health (PATH) study to probe the effects of the opening of commercial cannabis markets on cannabis and other substance use among individuals with psychosis (Aim 1). Next, I will utilize data from an NIH funded consortium of first episode psychosis clinics, the Early Psychosis Intervention Network (Epinet), to assess the effect of commercialization on substance use, psychosis relapse (emergency department visits and psychiatric hospitalizations), and secondary outcomes including criminal legal involvement among youth and young adults with early psychosis (Aim 2). Triple difference methodologies will be utilized in each analysis to measure whether commercialization is linked to health disparities, both between individuals with psychosis and the general population (Aim 1) and between majority and minoritized racial and ethnic individuals with psychosis (Aim 2). In the proposed training plan, I will develop expertise in: 1) substance use disorder research, policy, and implementation, 2) statistical methods for causal inference including difference in difference designs, and 3) rigorous analysis of health disparities to inform clinical and policy efforts to improve outcomes for vulnerable populations. The research will take place at the Cambridge Health Alliance, a public sector teaching hospital of Harvard Medical School, within the Health Equity Research Lab which has deep experience in health policy and health disparity research in large datasets. In line with NIDA’s strategic plan, this proposal will study “the effects of local, state, and national drug policies on public health” (Goal 1.3 2022-26) and will lay the foundation for my development into a leading health services and policy researcher straddling clinical and public health realms to develop substance use policies that maximize benefits and minimize harms for vulnerable populations. Subsequent R01 proposals will study the effects of commercialization on incidence of first episode psychosis in national claims data as well as the effects of public health policies (ex. marketing and advertising limits, health warnings, and potency limits) on individuals with serious mental illness.