Effects of frequent marijuana use on risky decision-making in young adult college students

Marijuana (MJ) is the most widely used illicit substance among adolescents and young adults. Frequent MJ use has been associated with impairments in cognitive flexibility and inhibition, both of which play important roles in decision-making. However, the impact of frequent MJ use on decision-making performance is mixed and not well understood. The current study examined the influence of frequent MJ use on risky decision-making in college students, 18-22 years old. Methods: From 2017 to 2019, data was collected from young adult college students (n = 65) consisting of 32 healthy controls (HC) and 33 frequent marijuana users (MJ+). Participants completed the Iowa Gambling Task (IGT), a measure of risky decision-making, and net IGT scores (advantageous-disadvantageous decisions) were used as a measure of optimal decision-making. Results: The main finding indicated there was a significant effect of group on net IGT scores (p = 0.018), which remained significant when sex was included in the model (p = 0.006), such that MJ+ had lower net IGT scores than HC. Conclusions: These findings highlight potential differences in risky decision-making between MJ+ and HC, but it is uncertain whether these differences are pre-existing and increase vulnerability for frequent MJ use or if they are related to the effects of frequent MJ use on decision-making.