The Impact of Cannabis Legalization on Cannabis, Nicotine and Alcohol Use among Youth with Mental Illness - PROJECT SUMMARY – Cambridge Health Alliance (CHA) Over the last decade, there has been a dramatic increase in the frequent and high-intensity use of nicotine vaping, cannabis, and alcohol use among adolescents and young adults (AYA), with increasing rates of days and times per month of vaping nicotine, cannabis and consuming alcohol. Remarkably, among adolescents with last month cannabis use, there has been a doubling of cannabis use disorder diagnoses from 29.2% in 2019 to 59.4% in 2022. Adolescents and young adults (AYA) with mental illness are particularly vulnerable to initiation of cannabis, nicotine, and alcohol (CNA) use and have more difficulty quitting, making this population an especially high priority for public health promotion. There have been massive shifts in public policy approaches to substance use in recent years, most notably recreational cannabis legalization (RCL). Emerging evidence shows RCL is linked to increases in cannabis, vaping nicotine and co-use of alcohol and cannabis among youth, but there remains a major gap in understanding of the effects of RCL among AYA with mental illness. This proposal seeks to fill that gap by utilizing a rigorous convergent parallel mixed methods design to a) assess the causal effects of RCL on CNA prevalence, intensity, risk perception, and disorder, and b) to contextualize results with qualitative interviews among AYA aged 12-25 with mental illness. In Aim 1a, we will analyze the 2010-2025 National Survey on Drug Use and Health (NSDUH) providing detailed information on CNA use and risk perception. In Aim 1b, we will analyze the 2018-2025 Population Assessment of Tobacco and Health (PATH) studies, capitalizing on longitudinal data to estimate highly controlled longitudinal causal inference methods (individual fixed effects models) and longitudinal outcomes (time from initiation to disorder). In Aim 2, we analyze comprehensive 50 state Medicaid claims data to assess the effect of RCL on hospitalizations related to CNA misuse and intoxication. In Aim 3, we will conduct qualitative interviews with AYA to gather more nuanced data on the use and co-use of these substances as well as inform and contextualize our quantitative results to inform public policy. The research proposal was developed and will be carried out with intensive collaboration and engagement from AYA with mental illness, caregivers, the Cannabis Regulators Association (CANNRA), and leaders in cannabis and tobacco control and addiction medicine, and will provide actionable information for youth and caregiver groups, and state cannabis control and tobacco control managers.
