Lautenbacher Stefan, Horn-Hofmann Claudia, Capito Eva Susanne, Wolstein Jörg, Kunz Miriam
Physiological Psychology, Otto-Friedrich University of Bamberg, Bamberg, Germany.
Medical Psychology and Sociology, Medical Faculty, University of Augsburg, Augsburg, Germany.
Eur J Pain. 2025 Sep;29(8):e70091. doi: 10.1002/ejp.70091.
Alcohol in sub-toxic dosages has appeared to slightly reduce experimental pain in psychophysical paradigms. However, this effect may also reflect impaired scaling performance in subjective ratings. To address this, we additionally assessed facial responses as a more direct and cognitively unbiased pain measure, while acknowledging the potential confound of alcohol's effects on motor inhibitory function.
We investigated 41 healthy participants (22 females) in a randomised, double-blind, and placebo-controlled design; targeting two moderate breath-alcohol levels (0.6‰, 0.8‰). Before and after an alcoholic or placebo drink, painful heat stimuli were applied to the forearm. Facial responses were analysed using the Facial Action Coding System (FACS). Subjective responses were assessed using a Numerical Rating Scale (NRS). To control for alcohol's effects on motor inhibitory function, participants completed the antisaccade task, which assesses inhibitory control over reflexive motor responses (eye movement).
While pain ratings were unaffected, alcohol significantly affected facial responses to pain, with the high alcohol dose leading to increased facial responses. Moreover, alcohol also led to a decrease in inhibitory control, with poorer performance in the antisaccade task. Not surprisingly, we found a significant association between the alcohol-induced increase in facial responses and the alcohol-induced decrease in inhibitory control.
Alcohol-induced motor disinhibition likely enhanced facial responses to pain without altering the subjective pain experience. In consequence, individuals under the influence of alcohol may facially display stronger pain levels (than experienced), which should not be interpreted as intentional exaggeration by clinicians involved in pain assessment.
Subtoxic doses of alcohol are known to produce weak analgesic effects. In contrast, the facial responses to pain were elevated under alcohol in the present study; probably due to an alcohol-induced motor disinhibition. Thus, individuals under the influence of alcohol may be analgized while in parallel being facially overly pain responsive.
亚中毒剂量的酒精似乎能在心理物理学范式中略微减轻实验性疼痛。然而，这种效应也可能反映出主观评分中量表使用能力的受损。为了解决这一问题，我们额外评估了面部反应，将其作为一种更直接且认知上无偏差的疼痛测量方法，同时认识到酒精对运动抑制功能影响这一潜在混杂因素。
我们采用随机、双盲、安慰剂对照设计对41名健康参与者（22名女性）进行了研究；目标是达到两个中度呼气酒精水平（0.6‰，0.8‰）。在饮用酒精饮料或安慰剂前后，将疼痛热刺激施加于前臂。使用面部动作编码系统（FACS）分析面部反应。使用数字评分量表（NRS）评估主观反应。为了控制酒精对运动抑制功能的影响，参与者完成了反扫视任务，该任务评估对反射性运动反应（眼球运动）的抑制控制。
虽然疼痛评分未受影响，但酒精显著影响了面部对疼痛的反应，高酒精剂量导致面部反应增加。此外，酒精还导致抑制控制能力下降，反扫视任务表现变差。不出所料，我们发现酒精引起的面部反应增加与酒精引起的抑制控制能力下降之间存在显著关联。
酒精引起的运动去抑制可能增强了面部对疼痛的反应，而没有改变主观疼痛体验。因此，受酒精影响的个体可能在面部表现出更强的疼痛程度（比实际经历的更强烈），参与疼痛评估的临床医生不应将其解释为故意夸大。
已知亚中毒剂量的酒精会产生微弱的镇痛作用。相比之下，在本研究中酒精作用下对疼痛的面部反应增强；可能是由于酒精引起的运动去抑制。因此，受酒精影响的个体可能在镇痛的同时面部对疼痛过度敏感。
