Objective: To assess driving performance after consuming edible cannabis using a driving simulator, examining frequency of use, THC concentration, and rural versus urban settings.

Methods: Adults in Denver, Colorado (N=62), between 25 and 55 years old, were recruited from November 2023 to July 2024 and assigned to groups based on past 90-day cannabis use: daily (N=18), occasional (N=15), or no use (N=29). This within-subjects study compared driving performance (i.e., speed, lane departures per minute, and standard deviation of lateral placement (SDLP)) using a validated driving simulator at baseline pre-test and two post-consumption tests (52 and 119 minutes). Linear mixed models were used to evaluate performance.

Results: The daily-use group drove slower than the occasional-use group (3.44 mph slower (urban, p<0.01 post-1); 2.33 mph slower (p=0.04 post-2)) and the no-use group (2.91 mph slower (urban), 0.89 mph slower (rural), p<0.01 post-1; 2.77 mph slower (urban), 0.92 mph slower (rural), p<0.01 post-2)). Lane departures increased in the occasional-use group from 0.24 at pre-test to 0.52 in post-1 and 0.55 in post-2 (p<0.01). Their rural SDLP increased: post-1 (30.84 cm, p=0.02), post-2 (31.96 cm, p<0.01), versus pre-test (27.23 cm). This group had significantly greater change in lane departures than both the no-use group (0.26, p=0.02) and daily-use group (0.33, p<0.01) in post-1. In post-2, the change remained greater than the no-use group (0.26, p=0.02) and daily-use group (0.27, p=0.03).

Conclusion: Our study found significant changes in driving performance following edible cannabis use, including findings related to effect duration, use frequency, and road settings.