HIV Sexual Risk Behavior: Methamphetamine and Delay Discounting of Sexual Rewards

描述（由申请人提供）：除了共用静脉注射设备外，药物滥用传播艾滋病毒的媒介还包括精神兴奋剂滥用与艾滋病毒性风险行为和艾滋病毒感染增加的相关性。人们对导致性风险行为的决策过程知之甚少，特别是在兴奋剂滥用方面。与性风险行为潜在相关的决策过程是延迟折扣，这被认为是冲动的一个方面。延迟折扣是指延迟奖励会降低其主观价值的观察结果，并且通常在实验室研究中通过偏好较小的早于较大的晚奖励来索引。延迟折扣已被证明与药物滥用广泛相关，主要是通过研究表明，药物滥用个体具有较高的折扣率（即，更冲动，或价值未来的后果）比非滥用个人。几项动物研究表明，长期接触可卡因会导致食物延迟折扣的长期持续增加（即对较小的食物的偏好早于较大的食物），即使在长期戒断可卡因之后。主要研究者开发了一项新的任务，评估延迟性奖励的折扣。该任务使用临床相关的假设选择现在无保护的性行为与等待使用避孕套的性行为，参考被参与者判断为性需求的个人照片。滥用兴奋剂的个体的初步数据是系统的，表明性奖励的折扣符合人类和动物中其他奖励折扣的相同数学函数特征。此外，折扣的性奖励表现出良好的重测信度，在一个星期的时间间隔，并显示两个操纵的敏感性。参与者更倾向于立即无保护的性行为，以应对更理想的合作伙伴，并在回应合作伙伴判断最不可能有性传播疾病。本研究将系统地扩展这一研究路线，通过检查两种剂量的口服甲基苯丙胺和安慰剂在实验室中滥用兴奋剂的参与者中的影响，同时评估延迟的假设性和真实的金钱奖励的决策。主观性唤起的测量将提供关于药物对折扣的任何影响是否与药物引起的性动机增加有关或独立的数据。这项研究将提供甲基苯丙胺可能导致性风险行为的潜在影响的第一个实验证据（增加性奖励的延迟折扣，增加一般奖励的延迟折扣，增加性唤起）。最终，这个项目的完成将增加我们对性艾滋病毒风险行为的理解，为艾滋病毒预防和教育工作提供信息，并为检查性风险行为提供一个新的和经验开发的工具。

DESCRIPTION (provided by applicant): In addition to the sharing of intravenous injection equipment, a drug-abuse vector for HIV transmission involves the association of psychomotor stimulant abuse with increased HIV sexual risk behavior and HIV infection. Little is known about decision-making processes contributing to sexual risk behavior, particularly in stimulant 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. The Principal Investigator has developed a novel task assessing the discounting of delayed sexual rewards. 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 to be sexually desirable by the participant. Preliminary data in stimulant-abusing individuals are systematic, showing that the discounting of sexual rewards conforms to the same mathematical function characteristic of the discounting of other reinforcers in humans and animals. Furthermore, discounting of sexual rewards shows good test-retest reliability at a 1-week interval, and shows sensitivity to two manipulations. 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. This study will systematically extend this line of research by examining the effects of two doses of oral methamphetamine and placebo in stimulant-abusing participants in the laboratory while assessing decision making for delayed hypothetical sexual and real money rewards. A measure of subjective sexual arousal will provide data on whether any drug effects on discounting are related to or independent of increased sexual motivation resulting from the drug. The study will provide the first experimental evidence of potential effects of methamphetamine that might contribute to sexual risk behavior (increased delay discounting for sexual rewards, increased delay discounting for rewards generally, increased sexual arousal). Ultimately, completion of this project will increase our understanding of sexual HIV risk behavior, inform HIV prevention and education efforts, and provide a new and empirically developed tool for examining sexual risk behavior.