Psychology Department, American University, 4400 Massachusetts Ave NW, Washington, DC, 20016, USA.
Center for Decision Research, Waseda University, Tokyo, Japan.
Psychopharmacology (Berl). 2020 May;237(5):1447-1457. doi: 10.1007/s00213-020-05471-6. Epub 2020 Jan 29.
In a previous study, investigating choice between heroin and a non-drug alternative in animals and reductions in income (i.e., choices/day) caused the percentage of income spent on heroin to progressively decrease. In contrast, another study found that humans with opioid use disorder spent the majority of their income on heroin even though they had little income. Comparison of these two studies suggests that the seemingly conflicting results could be explained by differences in the underlying economy types of the choice alternatives.
The present experiment tested the hypothesis that the effect of income changes on choice between heroin and a non-drug alternative depends on economy type.
Rats chose between heroin and saccharin under three income levels. For the Closed group, the choice session was the only opportunity to obtain these reinforcers. For the Heroin Open group and the Saccharin Open group, choice sessions were followed by 3-h periods of unlimited access to heroin or saccharin, respectively.
As income decreased, the Closed and Heroin Open groups, but not the Saccharin Open group, spent an increasingly greater percentage of income on saccharin than on heroin. The Saccharin Open group, compared to the other groups, spent a greater percentage of income on heroin as income decreased.
Results confirm that the effects of income and economy type can interact and this may explain the apparently discrepant results of earlier studies. More generally, findings suggest that situations where heroin choice has little consequence for consumption of non-drug alternatives may promote heroin use.
在之前的一项研究中，在动物中研究了海洛因和非药物替代品之间的选择以及收入减少（即选择/天）对海洛因支出占收入的百分比的影响，结果表明，收入减少会导致海洛因支出占收入的百分比逐渐减少。相比之下，另一项研究发现，患有阿片类药物使用障碍的人尽管收入微薄，但仍将大部分收入用于购买海洛因。这两项研究的比较表明，这些看似矛盾的结果可以通过选择替代物的潜在经济类型的差异来解释。
本实验检验了这样一种假设，即收入变化对海洛因和非药物替代品之间选择的影响取决于经济类型。
在三种收入水平下，大鼠在海洛因和蔗糖之间进行选择。对于封闭组，选择阶段是获得这些强化物的唯一机会。对于海洛因开放组和蔗糖开放组，选择阶段后分别有 3 小时的时间可以无限制地获得海洛因或蔗糖。
随着收入的减少，封闭组和海洛因开放组，但不是蔗糖开放组，用于购买蔗糖的支出占收入的比例越来越大，而用于购买海洛因的支出占收入的比例越来越小。与其他组相比，蔗糖开放组随着收入的减少，用于购买海洛因的支出占收入的比例更大。
结果证实，收入和经济类型的影响可以相互作用，这可能解释了早期研究中明显不一致的结果。更普遍地说，研究结果表明，海洛因选择对非药物替代品的消费影响不大的情况可能会促进海洛因的使用。
