Department of Behavioral Sciences, University of Florida, Gainesville, FL 32610, USA Department of Prosthodontics, College of Dentistry, University of Florida, Gainesville, FL 32610, USA Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
Pain. 2010 Jul;150(1):153-160. doi: 10.1016/j.pain.2010.04.020. Epub 2010 May 23.
This study supports the hypothesis that healthy older adults exhibit decreased endogenous pain inhibition compared to younger healthy controls. Twenty-two older adults (56-77years of age) and 27 controls aged 20-49 participated in five experimental sessions following a training session. Each experimental session consisted of five 60-s trials in which the experimental heat stimulus was presented to the thenar eminence of the left palm with or without a conditioning stimulus (cold-water immersion of the foot). The temperature for the palm (44-49 degrees C) and foot (8-16 degrees C) was customized for each subject. The intensity of experimental pain produced by the contact thermode was continuously measured during the 60-s trial with an electronic visual analogue scale. No significant associations were found between subjects rating of concentration and the overall inhibitory effect. Older subjects failed to demonstrate conditioned pain modulation (CPM) and showed facilitation in the trials using painful concurrent immersion of the foot. A novel aspect of the study was that we recorded "pain offset" (i.e., after-sensations) and found that ratings for the older sample decreased at a slower rate than observed for the group of younger adults suggesting increased central sensitization among the older sample. Decrements in CPM could contribute to the greater prevalence of pain in older age. Since a number of neurotransmitter systems are involved in pain modulation, it is possible age-related differences in CPM are due to functional changes in these systems in a number of areas within the neuroaxis.
本研究支持这样一种假设，即与年轻的健康对照组相比，健康的老年人表现出内源性疼痛抑制减少。22 名年龄在 56-77 岁的老年人和 27 名年龄在 20-49 岁的对照组参加了五个实验，每个实验都包括五个 60 秒的试验，在这些试验中，实验性热刺激被施加到左手掌心的大鱼际，同时或不施加条件性刺激（足部冷水浸泡）。手掌（44-49 摄氏度）和足部（8-16 摄氏度）的温度是为每个受试者定制的。接触热电极产生的实验性疼痛强度在 60 秒的试验中用电子视觉模拟量表连续测量。在集中注意力评分与整体抑制作用之间没有发现显著的相关性。老年受试者未能表现出条件性疼痛调制（CPM），并且在足部同时进行疼痛浸泡的试验中表现出促进作用。该研究的一个新方面是，我们记录了“疼痛消退”（即，后感觉），并发现老年组的评分下降速度比年轻组慢，这表明老年组的中枢敏化程度增加。CPM 的减少可能导致老年人疼痛的发病率更高。由于许多神经递质系统参与疼痛调制，CPM 的年龄相关性差异可能是由于神经轴内许多区域的这些系统的功能变化所致。
