Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD 21224-6823, USA.
Exp Clin Psychopharmacol. 2010 Feb;18(1):99-107. doi: 10.1037/a0018333.
Studies have found that a variety of drug-dependent groups discount delayed rewards more than matched controls. This study compared delay discounting for a hypothetical $1,000 reward among dependent marijuana users, former dependent marijuana users, and matched controls. Discounting of marijuana was also assessed in the currently marijuana-dependent group. No significant differences in discounting were detected among the groups; however, currently dependent users showed a trend to discount money more than the other 2 groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana was significantly and positively correlated. Regression analyses indicated that delay discounting was more closely associated with tobacco use than marijuana use. A variety of questionnaires were also administered, including impulsivity questionnaires. Dependent marijuana users scored as significantly more impulsive on the Impulsiveness subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire than controls. However, the 3 groups did not significantly differ on several other personality questionnaires, including the Barratt Impulsivity Scale-11. The Stanford Time Perception Inventory Present-Fatalistic subscale was positively correlated with money and marijuana discounting, indicating that a greater sense of powerlessness over the future is related to greater delay discounting. Results suggest that current marijuana dependence may be associated with a trend toward increased delay discounting, but this effect size appears to be smaller for marijuana than for previously examined drugs.
研究发现，各种药物依赖群体对延迟奖励的折扣程度高于匹配对照组。本研究比较了依赖大麻者、前依赖大麻者和匹配对照组对假设的 1000 美元奖励的延迟折扣。在当前依赖大麻的群体中也评估了大麻的折扣。各组之间没有发现折扣的显著差异；然而，当前依赖者比其他 2 组更倾向于折扣金钱。在依赖大麻的群体中，大麻的折扣程度高于金钱，而且金钱和大麻的折扣呈显著正相关。回归分析表明，延迟折扣与烟草使用的关系比大麻使用更为密切。还进行了各种问卷调查，包括冲动性问卷。依赖大麻的使用者在 Eysenck 冲动性-冒险性-同理心问卷的冲动性分量表上的得分明显高于对照组。然而，这 3 组在其他几个人格问卷上没有显著差异，包括巴雷特冲动性量表-11。斯坦福时间感知量表现在-宿命主义分量表与金钱和大麻的折扣呈正相关，表明对未来的无力感越大，延迟折扣越大。结果表明，目前的大麻依赖可能与增加延迟折扣的趋势有关，但这种效果大小对大麻的影响似乎小于之前研究的药物。
