Cannabis Legalization and Polysubstance Use Disorders
We examined associations between state medical and recreational cannabis legalization (MCL, RCL) and polysubstance use disorders involving cannabis use disorder (CUD) using 2010–2022 Merative MarketScan Commercial Claims data for adults aged 18–64. Difference-in-differences models with staggered policy adoption assessed the prevalence of co-occurring CUD and alcohol, opioid, or tobacco use disorders (AUD, OUD, TUD), as well as incident diagnoses among individuals with prior substance use disorders. Cannabis legalization was not associated with changes in co-occurring CUD and AUD or TUD, although RCL was associated with a 66.9% reduction in co-occurring CUD and OUD. Among individuals with prior CUD, MCL and RCL were associated with lower incidence of subsequent AUD (14.4% and 22.7%, respectively) and OUD (20.7% and 44.6%, respectively). In contrast, RCL was associated with a 34.4% increase in incident CUD among individuals with prior TUD. These findings suggest that cannabis legalization may differentially influence patterns of polysubstance use disorders, with evidence of reduced subsequent alcohol and opioid use disorders among individuals with CUD but increased risk of CUD among individuals with tobacco use disorder following recreational cannabis legalization.
Speaker profile
Dr Jayani Jayawardhana is an Associate Professor in the Department of Health Management and Policy in the College of Public Health, at the University of Kentucky, USA, with a joint appointment in the Department of Pharmacy Practice and Science, College of Pharmacy, and a courtesy appointment in the Martin School of Public Policy and Administration. She earned her Ph.D. in Economics from the University of Virginia, USA. Her research focuses on the intersection of health economics, health policy, and substance use, with an emphasis on evaluating the effects of public policies on healthcare access, utilization, quality, and population health.
Weekly seminar series
As part of our Centre's vibrant research culture, we host a weekly seminar series. Visiting and invited researchers present current research relating to the economics of health and wellbeing, and the healthcare sector. Visitors are welcome to join these sessions where discussion and debate is encouraged.
For further information on our seminar series, please contact Trong-Anh.Trinh@monash.edu
Event Details
- Date:
- 15 July 2026 at 11:00 am – 12:00 pm
- Venue:
- Caulfield campus, Building H, level 2, room H2.24
- Categories:
- CHE Seminar; General
Description
We examined associations between state medical and recreational cannabis legalization (MCL, RCL) and polysubstance use disorders involving cannabis use disorder (CUD) using 2010–2022 Merative MarketScan Commercial Claims data for adults aged 18–64. Difference-in-differences models with staggered policy adoption assessed the prevalence of co-occurring CUD and alcohol, opioid, or tobacco use disorders (AUD, OUD, TUD), as well as incident diagnoses among individuals with prior substance use disorders. Cannabis legalization was not associated with changes in co-occurring CUD and AUD or TUD, although RCL was associated with a 66.9% reduction in co-occurring CUD and OUD. Among individuals with prior CUD, MCL and RCL were associated with lower incidence of subsequent AUD (14.4% and 22.7%, respectively) and OUD (20.7% and 44.6%, respectively). In contrast, RCL was associated with a 34.4% increase in incident CUD among individuals with prior TUD. These findings suggest that cannabis legalization may differentially influence patterns of polysubstance use disorders, with evidence of reduced subsequent alcohol and opioid use disorders among individuals with CUD but increased risk of CUD among individuals with tobacco use disorder following recreational cannabis legalization.
Speaker profile
Dr Jayani Jayawardhana is an Associate Professor in the Department of Health Management and Policy in the College of Public Health, at the University of Kentucky, USA, with a joint appointment in the Department of Pharmacy Practice and Science, College of Pharmacy, and a courtesy appointment in the Martin School of Public Policy and Administration. She earned her Ph.D. in Economics from the University of Virginia, USA. Her research focuses on the intersection of health economics, health policy, and substance use, with an emphasis on evaluating the effects of public policies on healthcare access, utilization, quality, and population health.
Weekly seminar series
As part of our Centre's vibrant research culture, we host a weekly seminar series. Visiting and invited researchers present current research relating to the economics of health and wellbeing, and the healthcare sector. Visitors are welcome to join these sessions where discussion and debate is encouraged.
For further information on our seminar series, please contact Trong-Anh.Trinh@monash.edu