Cannabis-impaired driving among young adults showed mixed trends after Washington State opened retail stores | Research

The takeaway

In the five years after Washington State opened cannabis retail stores, alcohol-impaired driving decreased while cannabis-impaired driving held steady overall but decreased among cannabis users specifically.

Cannabis policy makers, traffic safety researchers, and legalization impact analysts

33% of cannabis users reported driving impaired in 2019

What the researchers found

From 2014 to 2019, alcohol DUI decreased overall (AOR 0.93) and among drinkers (AOR 0.95). Cannabis DUI did not change overall (11% by 2019) but decreased significantly among cannabis users (AOR 0.91; 33% by 2019). DUI after combined use showed a non-significant decrease. All prevalence rates remained at concerning levels.

Why it matters

One of the biggest concerns about cannabis legalization is increased impaired driving. This five-year post-legalization trend analysis provides reassurance that cannabis DUI did not increase while also highlighting that rates remain unacceptably high.

The numbers in context

12,963 participants; DUI-alcohol decreased (AOR 0.93, overall; 10% by 2019); DUI-cannabis stable overall (11% by 2019); DUI-cannabis decreased among users (AOR 0.91; 33% of users by 2019); DUI-combined trended down non-significantly

How the study worked

Weighted logistic regressions analyzing annual Washington Young Adult Health Survey data from 12,963 participants aged 18-25 across 2014-2019, assessing yearly trends in alcohol, cannabis, and combined substance impaired driving following cannabis retail store openings.

What this study cannot tell us

Self-reported DUI; no comparison state or pre-legalization baseline; cannot attribute trends specifically to retail store openings versus other factors; Washington-specific results may not generalize; 18-25 age range only

How to read the evidence

Large annual statewide survey with five years of post-legalization data, though lacking a control comparison and relying on self-report.

When this study was published

2024 publication analyzing 2014-2019 data

The bigger picture

The decrease in alcohol DUI alongside stable overall cannabis DUI after retail legalization suggests fears of dramatically increased impaired driving were not realized, though one-third of cannabis users still reporting DUI is a major concern.

Questions still open

Why did cannabis DUI decrease among users but not overall? Is this because new cannabis users who entered after legalization have different DUI patterns? What prevention strategies could further reduce these rates?

Common questions

Did cannabis retail stores increase impaired driving?

Overall cannabis-impaired driving rates did not significantly change after stores opened, holding steady at about 11% of young adults. Among cannabis users specifically, impaired driving actually decreased over the five-year period. Alcohol-impaired driving also decreased during this time.

How many cannabis users drove impaired?

By 2019, about one-third (33%) of young adult cannabis users in Washington State reported driving under the influence. While this represents a decrease from earlier years, it remains an alarmingly high rate that underscores the need for targeted prevention efforts.

Read the original research

Young Adult Alcohol and Cannabis Impaired Driving After the Opening of Cannabis Retail Stores in Washington State.

Prevention science : the official journal of the Society for Prevention Research, 25(5), 749-759

View on PubMed ↗Publisher’s paper ↗

Citation

Hultgren, Brittney A; Calhoun, Brian H; Fleming, Charles B; Lyons, Vivian H; Rhew, Isaac C; Larimer, Mary E; Kilmer, Jason R; Guttmannova, Katarina. (2024). Young Adult Alcohol and Cannabis Impaired Driving After the Opening of Cannabis Retail Stores in Washington State.. Prevention science : the official journal of the Society for Prevention Research, 25(5), 749-759. https://doi.org/10.1007/s11121-024-01679-6