Project

Cannabis Legalization a Decade Later: A Longitudinal Study of Teens, Young Adults, and Parents in Washington State

Project Description

Nonmedical (recreational) cannabis use is now legal in many states, and additional states are considering legalization despite uncertainty about impacts on public health. This study looks at changes in cannabis use across the first decade following cannabis legalization; changes in alcohol use, nicotine use, and their co-use with cannabis following cannabis legalization; and whether psychosocial consequences of cannabis use change when recreational cannabis is legal. This knowledge is critical to inform policy, support efforts to maintain hard-won reductions in teen cannabis use since the 2000s, and promote responsible use by adults.

This study continues and expands upon the Seattle Social Development Project-The Intergenerational Project (SSDP-TIP), which aims to understand the impact of cannabis legalization on youth and parent cannabis and other drug use in Washington State. SSDP-TIP is the only study in Washington State with longitudinal data from youth and their parents beginning 10 years before legalization, and this project will stretch to 12 years post-legalization. Findings will inform the timing of efforts to prevent underage and problematic cannabis, tobacco, and alcohol use, and help to clarify public health impacts in the context of cannabis legalization.

In 2025 the project received supplemental funding from NIDA to explore the impact of cannabis retail markets in Washington.

The cannabis market in Washington has evolved rapidly since legalization, with ongoing expansion in the number of retail stores, declining prices, increasing product potency, and proliferation in the number and types of cannabis products available. The long-term implications of these market changes on health-risking patterns of cannabis use remain unclear. This new funding will be used to examine how cannabis store availability and marketplace characteristics shape long-term patterns of cannabis use among parents and youths in Washington. The project will use data from the Seattle Social Development Project – The Intergenerational Project (SSDP-TIP), led by principal investigator Jennifer Bailey, PhD, with analyses led by Dr. Vi Le. Findings from this administrative supplement will inform the development of regulatory policies that minimize underage and health-risking cannabis use behaviors.