Driving after Use of Marijuana: Young Adults

Background and Purpose: For over 40 years, marijuana has been one of the most widely used substances by young adults (Johnston et al., 2019). Tetrahydrocannabinol (THC), the primary psychoactive component in marijuana, has been shown to negatively impact driving performance (Hartman & Huestis, 2013; Ronen et al., 2008, 2010). Despite the potential risk, use of marijuana while driving has increased over time (U.S. NHTSA, 2015). Identifying correlates of driving after using marijuana is of great importance in informing prevention efforts, particularly as marijuana becomes increasingly available with more states legalizing marijuana for recreational use. Few studies have examined the use of marijuana while driving among the young adult population, despite the fact that this age group has the highest rates of marijuana use (NIDA, 2017). The current study examined rates and correlates of driving after using marijuana among young adult marijuana users.

Methods: Young adults ages 18-25 (N=2058) were recruited through paid Facebook advertising to complete an online health survey between February and March 2018. The current study focuses on participants who reported past month marijuana use (n=436). Participants were asked about demographic characteristics (e.g, sex, race, age, employment status, student status), frequency of marijuana use in the past month, whether they had a medical marijuana card, coping motives for using marijuana (e.g. to relax or relieve tension, to get away from problems or troubles, because of anger or frustration, to get through the day), and whether they had driven after using marijuana. Binary logistic regression was used to examine predictors of driving after using marijuana.

Results: Nearly a third (32.6%) of the sample reported driving after using marijuana in the past month. Young adults who used marijuana more often (OR = 1.09, p < .001) and those who endorsed coping motivations for use (OR = 2.56, p = .038) had greater odds of driving after using marijuana. Young adults who were unemployed had lower odds of driving after using marijuana (OR = 0.50, p= .045). No differences in driving after using marijuana were found based on gender, race, age, student status, and having a medical marijuana card.

Conclusions and Implications: Among young adults who recently used marijuana, driving after use of marijuana was fairly common (32.6%). Findings indicate a relationship between driving after using marijuana and coping motivations for marijuana use. Addressing coping motives in treatment, as well as developing prevention efforts that address coping motives may help those youth at the greatest risk of driving after use of marijuana. Further research should continue examining driving after marijuana use among young adults, as well as methods to address coping motives behind marijuana use.