In addition to the sharing of intravenous injection equipment, a major contribution of drug abuse to HIV risk involves the association of cocaine abuse with increased HIV sexual risk behavior and HIV infection. Little is known about decision-making processes contributing to sexual risk behavior, particularly in cocaine abuse. A decision-making process of potential relevance to sexual risk behavior is delay discounting, which is considered an aspect of impulsivity. Delay discounting refers to the observation that delaying a reward reduces its subjective value, and is typically indexed in laboratory studies by preference for smaller sooner over larger later rewards. Delay discounting has been shown to be widely relevant to drug abuse, primarily by studies showing that drug-abusing individuals have higher discounting rates (i.e., are more impulsive, or value future consequences less) than non-abusing individuals. Several animal studies show that chronic exposure to cocaine causes long lasting increases in delay discounting for food reinforcers (i.e. preference for smaller sooner over larger later food), even after prolonged abstinence from cocaine. Under an R21 grant the principal investigator developed a novel task assessing the discounting of delayed sexual rewards (i.e., sexual discounting). The task uses clinically relevant hypothetical choices between unprotected sex now vs. waiting for sex with a condom, in reference to the photograph of an individual judged as sexually desirable by the participant. Preliminary data in cocaine-abusing individuals suggest that the discounting of sexual rewards correlates with self-report sexual risk behavior, and follows the same mathematical form characteristic of the discounting of other rewards in humans and animals. Furthermore, discounting of sexual rewards was sensitive to two manipulations. That is, participants were more likely to prefer immediate unprotected sex in response to more desirable partners, and in response to partners judged least likely to have a sexually transmitted disease. Two studies are proposed that will systematically extend this line of research to determine the relationship between sexual discounting and HIV sexual risk behavior among cocaine-abusing individuals. One study will test whether cocaine-abusing individuals show greater sexual discounting than matched control non-drug users to determine if sexual discounting relates to cocaine abuse status. The second study will administer placebo and 2 doses of oral cocaine to non-treatment seeking cocaine-abusing individuals to determine the causal role of cocaine intoxication on sexual discounting. Collectively, these studies will develop and provide clinically meaningful data on a new and empirically supported tool for examining sexual risk behavior. Ultimately, completion of this project will increase our understanding of sexual HIV risk behavior and therefore inform HIV prevention and education efforts.
Two studies will be conducted in order to understand the basic-decision making mechanisms that drive the high rates of HIV sexual risk behavior and HIV infection rates in cocaine-abusing individuals. More specifically, the studies will explore whether the devaluation of future consequences (called delay discounting) is a factor that underlies HIV sexual risk behavior. Because risk behavior associated with cocaine abuse is known to result in public health harms through sexual HIV risk behavior, these studies will improve HIV prevention and education efforts within cocaine-abusing individuals by determining which decision-making processes are most relevant to risk behavior.
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