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

说明(申请人提供)：除了共用静脉注射设备外，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行为增加和艾滋病毒感染之间的关联。人们对导致性危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。延迟折扣指的是观察到延迟奖励会降低其主观价值，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指标化的。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，吸毒者比非滥用者有更高的折扣率(即更冲动，或更不看重未来的后果)。几项动物研究表明，即使在长期戒除可卡因之后，长期接触可卡因也会导致食物增强剂延迟折扣的长期增加(即更喜欢较早较小的食物，而不是较大的较晚食物)。首席调查员制定了一项新的任务，评估延迟的性奖励的折扣。这项任务使用了临床上相关的假设选择，即现在无保护措施的性行为和等待戴避孕套的性行为之间的选择，参照参与者判断为性欲的个人的照片。兴奋剂滥用个体的初步数据是系统的，表明折扣性奖励符合相同的数学函数特征，即在人类和动物中折算其他增强剂。此外，打折性奖赏在1周的间隔内表现出良好的重测信度，并且对两种操纵方式表现出敏感性。参与者更倾向于立即进行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上性传播疾病的伴侣。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，说明任何药物对折扣的影响是否与药物引起的性动机增强有关或独立于药物引起的性动机增强。这项研究将首次提供甲基苯丙胺可能导致性行为风险的潜在影响的实验证据(增加了对性奖励的延迟折扣，普遍增加了对奖励的延迟折扣，增加了性唤起)。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，并为检查性风险行为提供一个新的、经验性开发的工具。

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.