ABSTRACT The COVID-19 pandemic has disrupted lives and affected behavioral health of many. Unhealthy changes in substance use are a great concern. Early data indicate substance use has changed during the pandemic, particularly for some sub-groups of the population. This project aims to examine changes in cannabis, alcohol, and tobacco use and related health risk behaviors (i.e. driving while—or riding with a driver—under the influence of cannabis, alcohol, and simultaneous effects of cannabis and alcohol) during the course of COVID- 19 pandemic among young adults in Washington State. Specifically, we will address the following questions: What are the patterns of young adult substance use during the pandemic and how do these relate to use before the pandemic both in terms of individual trajectories and normative patterns over the course of young adulthood? What are the predictors of escalation of use vs. desistance from use during the pandemic and what is the role of pandemic stressors in these processes? How do community-level differences in access to resources and access to substances relate to patterns of substance use during the pandemic? To answer these questions, we will use data from the WA Young Adult Health Survey (YAHS) that we collected over the past 7 years with funding from the WA State’s Division of Behavioral Health and Recovery. YAHS is an accelerated longitudinal cohort sequential study of young adults ages 18-25, with cohorts added annually and followed over time (2015-2021). Two cohorts were added after the onset of the pandemic, and five cohorts have longitudinal data spanning the time from before to during the pandemic. These data will be linked with community-level variables (e.g., neighborhood disadvantage, availability of substance use-related outlets and services) before and during the COVID-19 pandemic. We will assess changes in patterns (e.g., mode of use, sources, frequency, and amount) of cannabis, alcohol, and tobacco use, simultaneous cannabis and alcohol use, and SU-related risk behaviors (e.g., driving while intoxicated) from before to during the pandemic. The role of community-level factors and differences by socio-demographic characteristics (e.g., sex, sexual and gender minoritized status, race/ethnicity, college student status) in these changes will be examined. Moreover, we will examine within-person changes in risk factors such as norms and perceived harm of cannabis, tobacco, and alcohol use and COVID-19 pandemic related stressors by socio-demographic and community-level characteristics. Finally, we will assess within-person changes in substance use and related risk behaviors (e.g., driving while intoxicated), focusing specifically on initiation, escalation, and desistance and their predictors and potential explanatory mechanisms. Findings will inform planning of prevention and intervention efforts aimed at improving health and reducing problem behaviors.

PROJECT NARRATIVE The present application proposes to conduct secondary analyses of accelerated longitudinal cohort sequential data from the Washington State Young Adult Health Study. The project will examine changes in young adult substance use, related risk behaviors, and substance use related risk factors from before to during the COVID- 19 pandemic among young adults in a state where alcohol, tobacco, and cannabis sales and use are legal for adults age 21 and over. Findings from the proposed project will inform tailoring and development of prevention and intervention efforts aimed at reducing problem behaviors and improving public health in a situation that poses serious challenges for effective long-term planning of such efforts.