Pass the Keys: Using Behavioral Economics to Explore Driving After Cannabis Use.

Background: Controlled studies show cannabis impairs driving performance and may increase crash risk. Recent approaches in behavioral economics have used marijuana purchase tasks (MPTs) to understand driving after cannabis use (DACU). One factor that may influence DACU is the latency between smoking and having to drive.

Method: A crowdsourced sample of adults who smoke cannabis at least monthly (n = 167; 77% White; 45% women; mean age = 38.55) completed 4 MPTs in the context of different instructional vignettes with different smoked cannabis use and driving latencies (non-driving; 20 minutes, 1 hour, and 6 hours). Participants reported frequency and perceived dangerousness of DACU. Demand indices included intensity (consumption when free), breakpoint (last price with any consumption), O_max (maximum expenditure), and P_max (price at O_max).

Results: Repeated measures analysis of variance revealed main effects of latency on all demand indices (ps <0.001), attributed to lower demand in each of the DACU conditions relative to the non-driving condition (ps <0.015; ds = 0.09-1.52). Demand increased in a linear fashion as latency increased. Participants with a history of DACU showed a blunted reduction in demand (except breakpoint) at each latency compared to participants with no DACU history (ps <0.043; η_p² = 0.008-0.043). Perceived dangerousness was inversely correlated with demand (except breakpoint; rs -0.29 to -0.62, ps <0.05).

Conclusions: Cannabis demand is sensitive to specific parameters surrounding driving contingencies, and risk perceptions may contribute to these associations. Future research is needed to extend these findings and identify other factors impacting DACU, such as different routes of administration or road conditions.