Examining Longitudinal Associations Between Trauma Exposure and Temperament on Marijuana Use in Legalized and Non-Legalized States

INTRODUCTION: Legalization of marijuana in the United States continues to be a controversial topic, despite evidence indicating little or no increase in use following decriminalization. Most research has focused on changes in use following legalization, while other factors influencing use have largely been overlooked. Importantly, experience of trauma has been linked to cannabis use and earlier onset of use. Given that certain temperamental characteristics are related to trauma exposure, we compared associations between trauma, temperament, and cannabis use prior to the legalization of recreational use in three states and one district as compared to associations in individuals living in states that have not legalized recreational use, with plans for observing associations after legalization.

METHODS: Current sample of women (n=319; mean age=24.83 years) consisted of birth mothers in the Early Growth Development Study- an ongoing longitudinal study of birth and adoptive families. Trauma was assessed using a cumulative score of lifetime number of traumatic events. Temperament characteristics of inhibitory control, effortful control, and attentional control were assessed using their respective scales on the Adult Temperament Questionnaire. Lifetime marijuana use (yes/no) and onset of use were assessed using items from the Composite International Diagnostic Interview. State of residence prior to legalization was categorized based on legalization policy (i.e., women living in states/district that recently legalized recreational use [n=115] vs. states that have not legalized recreational use [n=204]).

RESULTS: We found a significant association between marijuana use and trauma (t(160)=3.55, p=.001), and a negative association between age of onset of marijuana use and exposure to trauma (r=-0.26, p<.001). Trauma exposure was correlated with inhibitory control (r=-0.13, p=.03), effortful control (r=-0.24, p<.001), and attentional control (r=-0.21, p<.001). Marijuana use was also related to lower effortful control (t(142)=3.89, p<.001) and lower attentional control (t(125)=-2.42, p=.02), whereas age of first use correlated positively with attentional control (r=0.21, p=.002). As expected, there were no significant differences in these relations between women in states that were eventually legalized vs. non-legalized. To extend our findings, we will next examine associations between trauma exposure and frequency and onset of marijuana use after legalization, with temperament as a moderator.

CONCLUSION: Our results were consistent with previous findings illustrating a relationship between trauma exposure and marijuana use; specifically, women who engaged in marijuana use experienced more traumatic incidents, and those who had used marijuana at an earlier age were exposed to more trauma over their lifetime. Additionally, greater trauma exposure and marijuana use were related to lower self-regulatory control. Understanding the effects of trauma and temperament on marijuana use before and after legalization of recreational use is critical in informing policy on drug use, and in identifying factors outside decriminalization that contribute to legal and illegal marijuana use.