Department of Psychology, University of Illinois Chicago, 1007 W. Harrison St, Chicago, IL, 60607, USA.
Department of Psychiatry and Behavioral Neuroscience, University of Chicago, 5841 S. Maryland Ave, Chicago, IL, 60637, USA.
Psychopharmacology (Berl). 2022 May;239(5):1487-1497. doi: 10.1007/s00213-021-06032-1. Epub 2022 Feb 1.
The use of cannabis has been clinically associated with decreased motivation to engage in normally rewarding activities. However, evidence from previous controlled studies is mixed.
In this study, we examined the effects of acute delta-9-tetrahydrocannabinol (THC) versus placebo on a task measuring willingness to exert effort for rewards. This is a secondary analysis of a larger study examining interactions between ovarian hormones and THC. In this within-subjects study, oral THC and placebo were administered under double-blind conditions in counterbalanced order to healthy young adult (M age = 24 years) women with previous cannabis experience who were not regular users. Forty subjects completed three 4-h sessions with PL, 7.5 and 15 mg THC, while an additional 18 completed only PL and 15 mg THC sessions (design abridged due to pandemic). At each session, they completed a task consisting of making repeated choices between a hard and an easy task, which were worth varying amounts of money at varying probabilities.
THC dose-dependently decreased hard task choices (drug effect, b = - 0.79, SE = 0.29, z = - 2.67, p < 0.01), especially at moderate to high expected values of reward (drug × probability × amount interaction, b = 0.77, SE = 0.38, z = 1.99, p = 0.04). THC also slowed task performance (drug effect, b = 0.01, SE = 0.005, t(5.24) = 2.11, p = 0.04), but the effect of THC on choice was still significant after controlling for this psychomotor slowing.
These findings support the idea that cannabis acutely reduces motivation to earn non-drug rewards. Still to be determined are the neurochemical mechanisms underlying this effect.
大麻的使用已在临床上与降低从事正常奖励活动的动机相关联。然而，来自先前对照研究的证据是混杂的。
在这项研究中，我们检查了急性 delta-9-四氢大麻酚（THC）与安慰剂对衡量为奖励付出努力的意愿的任务的影响。这是一项检查卵巢激素与 THC 之间相互作用的更大研究的二次分析。在这项单盲、自身对照研究中，向有先前大麻使用经验但非常规使用者的健康年轻成年（M 年龄= 24 岁）女性口服 THC 和安慰剂，并以随机顺序给药。40 名受试者完成了 3 次 4 小时的 PL、7.5 和 15 mg THC 试验，而另外 18 名受试者仅完成了 PL 和 15 mg THC 试验（由于大流行而简化设计）。在每个试验中，她们完成了一项由在困难任务和简单任务之间进行反复选择组成的任务，这两个任务的价值在不同的概率下有所不同。
THC 剂量依赖性地减少了困难任务的选择（药物效应，b=−0.79，SE=0.29，z=−2.67，p<0.01），尤其是在中等至高奖励预期值时（药物×概率×数量交互作用，b=0.77，SE=0.38，z=1.99，p=0.04）。THC 还减慢了任务表现（药物效应，b=0.01，SE=0.005，t(5.24)=2.11，p=0.04），但在控制这种精神运动速度减慢后，THC 对选择的影响仍然显著。
这些发现支持大麻急性降低获得非药物奖励的动机的观点。仍有待确定的是这种效应的神经化学机制。
