The primary goal of the proposed project is to improve understanding of the emotional and behavioral processes that are associated with chronic marijuana use and deprivation. Specifically, we will investigate emotional responses and behavior in an economic decision making task in deprived daily marijuana users, non-deprived daily marijuana users, and an additional non-using comparison group. Participants will complete a decision making task in which they choose between certain and uncertain (probabilistic) reward offers to determine how they subjectively value different types of rewards. The task will be completed within alternating blocks of unpredictable electric shock and no-shock, respectively, to examine how anxiety resulting from unpredictable shock may bias decision making. Participants'startle response (a physiological measure of emotional response) to will be recorded, and their choices in the decision making task will be evaluated to determine biases in decision making. Based on our previous research and the extant literature, we predict that deprived marijuana users will show increased startle response to unpredictable shock (i.e. anxiety) as compared to the other two groups. In addition, we predict that deprived marijuana users will show a heightened preference for certain reward options in the decision making task, and that the anxiety manipulation will augment this bias in all groups, particularly in the deprived marijuana users. The study of emotional outcomes and decision making in daily marijuana users is highly relevant to public health, as marijuana is the most commonly used illicit drug. Given progressively high rates of use, and increasing legislative efforts related to marijuana legalization, decriminalization, and/or government-sanctioned, regulated production and distribution of marijuana, greater scientific and federal scrutiny of individuals'motivation for use, and the outcomes associated with chronic use, dependence, and deprivation, is warranted. How use affects emotional processes and subsequent decision making is critical in answering these questions. Importantly, numerous important links between anxiety and drug use have been documented, and further understanding of these mechanisms will help to improve treatment development and outcomes. As aforementioned, this information is of great import to policymakers as well. Finally, the use of a cross-species procedure and dependent measure (i.e. the startle reflex) suggests that this particular research project can provide a critical translational link between preclinical work and human addiction research in this area.

Public Health Relevance

Marijuana is the most commonly used illicit drug, with approximately 42% of people in the United States reporting that they have used marijuana in their lifetime and increasing rates of young adults reporting use in recent years (SAMHSA, 2010). With increased legislative efforts being advanced relating to marijuana decriminalization and/or legalization for medicinal and/or personal use, a better understanding of motivation for use and the behavioral and emotional outcomes associated with use, dependence and withdrawal is warranted and timely. This information would serve to better guide policy, treatment development, and prevention efforts by enabling us to determine its addictive potential and which individuals may be at risk for becoming dependent, as well as how to tailor treatments in order to better prepare individuals to avoid and/or manage negative outcomes associated with use and dependence.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1-F12B-U (20))
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Bjork, James M
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University of Wisconsin Madison
Schools of Arts and Sciences
United States
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Hefner, Kathryn R; Starr, Mark J (2017) Altered subjective reward valuation among female heavy marijuana users. Exp Clin Psychopharmacol 25:1-12
Hefner, Kathryn R; Starr, Mark J; Curtin, John J (2016) Altered subjective reward valuation among drug-deprived heavy marijuana users: Aversion to uncertainty. J Abnorm Psychol 125:138-50