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

描述（由申请人提供）：除了共享静脉注射设备外，艾滋病毒传播的药物滥用媒介还涉及精神运动兴奋剂滥用与艾滋病毒性风险行为和艾滋病毒感染增加之间的关联。人们对决策过程对性危险行为的影响知之甚少，特别是在兴奋剂滥用方面。一个与性风险行为潜在相关的决策过程是延迟折扣，这被认为是冲动性的一个方面。延迟折扣指的是延迟奖励会降低其主观价值的观察结果，在实验室研究中通常是通过偏好较小的较早奖励而不是较大的较晚奖励来索引的。延迟折扣已被证明与药物滥用广泛相关，主要是研究表明，滥用药物的人比不滥用药物的人有更高的贴现率（即，更冲动，或更不重视未来的后果）。几项动物研究表明，即使在长期戒断可卡因之后，长期接触可卡因也会导致对食物强化物的延迟折扣长期增加（即对较小的食物的偏好，而不是较大的食物）。首席研究员开发了一项新任务，评估延迟性奖励的折扣。这项任务使用临床相关的假设选择，在现在无保护的性行为和等待戴上避孕套的性行为之间，参考被参与者认为具有性吸引力的个体的照片。兴奋剂滥用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强化物折扣的相同数学函数特征。此外，性奖励折扣在1周间隔内表现出良好的重测信度，并且对两种操作表现出敏感性。参与者更倾向于立即发生无保护措施的性行为，以回应更理想的伴侣，以及被认为最不可能患有性传播疾病的伴侣。这项研究将系统地扩展这一研究路线，在实验室中检查两种剂量的口服甲基苯丙胺和安慰剂对兴奋剂滥用参与者的影响，同时评估延迟假设性奖励和真实金钱奖励的决策。主观性唤起的测量将提供数据，说明药物对折扣的影响是否与药物引起的性动机增加有关或独立。这项研究将提供甲基苯丙胺可能导致性危险行为的潜在影响的第一个实验证据（对性奖励的延迟折扣增加，对奖励的延迟折扣增加，性唤起增加）。最终，该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，并提供一种新的、经验开发的性风险行为检查工具。

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.