Neural Correlates of Choices for Impulsive HIV-risk Behavior in Stimulant Dependence

Virginia Polytechnic Inst And St Univ, Blacksburg VA

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Abstract

? DESCRIPTION (provided by applicant): Illicit stimulant use and dependence remain significant problems in the United States today (NIDA, 2010). Two of the major health concerns with stimulant dependent individuals is the increased rate of sexual HIV-risk behavior in this group and a corresponding increased rate of HIV infection (e.g., Molitor et al., 1999). While the relationship between increased HIV-related sexual risk behavior and stimulant dependence is well established, the decision making processes that underlies the choice to engage in risky sex is not well characterized. A fronto-parietal-limbic network is known to be involved the assignment of value to immediate and delayed outcomes in delayed discounting tasks that measure how delayed rewards lose their value when delayed (McClure et al., 2004, 2007), and stimulant-dependent participants differentially recruit this network (Monterosso et al., 2007). The recently developed sexual discounting task (Johnson & Bruner, 2012, 2013) is a measure of HIV risk that is similar to a monetary discounting task, but assesses how the decision to engage in hypothetical risky sex changes as a function of the delay to condom availability, thereby obtaining a safe-sex discount rate. We have collected preliminary data showing that safe-sex discount rates are much higher in cocaine-dependent participants than non-dependent controls, as well as in males compared to females. The proposed research will help illuminate the poorly understood decision-making processes about gender and risky sex in stimulant-dependent participants and controls by directly comparing BOLD response using fMRI in fronto-parietal-limbic valuation networks during decisions about engaging in risky sex and delayed money. Examining interaction effects between these variables will allow us to determine whether the effect of stimulant dependence on safe-sex discount rates depends on gender (or vice versa), or if these factors affect decision- making independently. We propose to compare discount rates and associated brain activation of the sex discounting and monetary discounting tasks in cocaine dependence vs controls (Specific Aim 1) and between males and females (Specific Aim 2), and the interaction between these. We will measure BOLD response using fMRI while participants make choices between immediate risky sex and safer sex that is delayed by various durations of time. We will also explore the role of risky sexual practices and race in an Exploratory Aim. Together, these aims will address the decision-making processes underlying risky sexual behavior in both stimulant users and non-stimulant users, and could inform future research to predict, prevent, and treat risky sexual behavior in both stimulant-dependent and non-dependent populations.