Physiological Psychology, Otto-Friedrich University Bamberg, Bamberg, Germany.
Gerontology. 2009;55(6):674-82. doi: 10.1159/000235719. Epub 2009 Aug 20.
Both age and dementia have been shown to have an effect on nociception and pain processing. The question arises whether mild cognitive impairment (MCI), which is thought to be a transitional stage between normal ageing and dementia, is also associated with alterations in pain processing.
The aim of the present study was to answer this question by investigating the impact of age and MCI on the pain response system.
Forty young subjects, 45 cognitively unimpaired elderly subjects and 42 subjects with MCI were investigated by use of an experimental multi-method approach. The subjects were tested for their subjective (pain ratings), motor (RIII reflex), facial (Facial Action Coding System) and their autonomic (sympathetic skin response and evoked heart rate response) responses to noxious electrical stimulation of the nervus suralis.
We found significant group differences in the autonomic responses to noxious stimulation. The sympathetic skin response amplitude was significantly reduced in the cognitively unimpaired elderly subjects compared to younger subjects and to an even greater degree in subjects with MCI. The evoked heart rate response was reduced to a similar degree in both groups of aged subjects. Regression analyses within the two groups of the elderly subjects revealed that age and, in the MCI group, cognitive status were significant predictors of the decrease in autonomic responsiveness to noxious stimulation. Except for the autonomic parameters, no other pain parameter differed between the three groups.
The pain response system appeared to be quite unaltered in MCI patients compared to cognitively unimpaired individuals of the same age. Only the sympathetic responsiveness qualified as an indicator of early aging effects as well as of pathophysiology associated with MCI, which both seemed to affect the pain system independently from each other.
年龄和痴呆已被证明对伤害感受和疼痛处理有影响。问题是，轻度认知障碍（MCI）被认为是正常衰老和痴呆之间的过渡阶段，是否也与疼痛处理的改变有关。
本研究旨在通过研究年龄和 MCI 对疼痛反应系统的影响来回答这个问题。
采用实验多方法的方法，对 40 名年轻受试者、45 名认知正常的老年受试者和 42 名 MCI 受试者进行了研究。通过对周围神经腓肠神经的有害电刺激，对受试者的主观（疼痛评分）、运动（RIII 反射）、面部（面部动作编码系统）和自主（交感皮肤反应和诱发心率反应）反应进行了测试。
我们发现，在自主对有害刺激的反应方面，各组之间存在显著差异。与年轻受试者相比，认知正常的老年受试者的交感皮肤反应幅度显著降低，而 MCI 受试者的降低更为明显。两组老年受试者的诱发心率反应均降低到相似程度。在两组老年受试者中进行的回归分析显示，年龄和认知状态是自主反应对有害刺激降低的显著预测因素。除了自主参数外，三组之间的其他疼痛参数没有差异。
与同龄认知正常的个体相比，MCI 患者的疼痛反应系统似乎没有明显改变。只有交感反应可以作为早期衰老效应以及与 MCI 相关的病理生理学的指标，这两者似乎都独立于彼此影响疼痛系统。
