Changes in Local Community Spatial Trends of Motor Vehicle Accidents Near Cannabis Dispensaries after Recreational Cannabis Legalization

Introduction: In recent years, the impact of recreational cannabis legalization (RCL) on road safety and motor vehicle accidents (MVAs) has become a growing area of research, given increasing cannabis legalization and the impact of cannabis on motor control and attention. In 2023, Connecticut legalized recreational cannabis, and this study explored changes in MVAs both in a statewide analysis and in the local vicinity of recreational cannabis dispensaries. Materials and Methods: We conducted an ecological study to assess the impact of recreational cannabis dispensaries on MVAs in Connecticut after legalization on January 10, 2023. Using crash data from Connecticut and Maryland (as a control) for two 24-week periods before and after legalization, we performed a difference-in-differences analysis with negative binomial regression, controlling confounders. At the dispensary level, we compared MVAs within an 800-m radius 8 weeks before and after opening, employing interrupted time series analysis with negative binomial mixed-effects regression models. Results: In the statewide analysis comparing Connecticut with Maryland over two 24-week periods before and after RCL in Connecticut, no significant effect on MVAs was found after adjusting for autocorrelation and seasonal variations (interaction term coefficient = −0.0391, p = 0.0696). In the local analysis, examining accident rates within an 800-m radius of 13 dispensaries over 8 weeks before and after their openings, the negative binomial mixed-effects model showed no significant change (incidence rate ratio = 1.10, 95% confidence interval: 0.74-1.64, p = 0.63). Discussion: These findings suggest that cannabis legalization and dispensary openings did not significantly impact motor vehicle accident rates during the study period.