Table_4_Better Executive Functions Are Associated With More Efficient Cognitive Pain Modulation in Older Adults: An fMRI Study.DOCX

Growing evidence suggests that aging is associated with less efficient endogenous pain modulation as demonstrated by reduced conditioned pain modulation, and that these changes may be mediated by differences in frontal functioning. Yet, little is known about potential age-related changes in cognitive pain modulation, such as distraction from pain. In a first session, 30 healthy young (19–35 years) and 30 healthy older (59–82 years) adults completed a battery of neuropsychological tests. In a second session, we acquired functional brain images while participants completed a working memory task with two levels of cognitive load (high vs. low) and concurrently received individually adjusted heat stimuli (warm vs. painful). In both age groups, completing the high load task was associated with a significant reduction in the perceived intensity and unpleasantness of painful stimuli and a reduction in activation of brain regions involved in pain processing. Group comparisons revealed that young adults showed a stronger de-activation of brain regions involved in pain processing during the high load vs. the low load task, such as the right insula, right mid cingulate cortex and left supramarginal gyrus, compared to older adults. Older adults, on the other hand, showed an increased activation in the anterior cingulate cortex during the high load vs. low load task, when compared to young adults. Covariate analyses indicated that executive functions significantly predicted neural pain modulation modulation in older adults: Better executive functions were associated with a more pronounced de-activation of the insula, thalamus and primary somatosensory cortex and increased activation of prefrontal regions during the high vs. low load task. These findings suggest that cognitive pain modulation is altered in older age and that the preservation of executive functions may have beneficial effects on the efficacy of distraction from pain.

越来越多的证据表明，衰老与内源性疼痛调控（endogenous pain modulation）效率降低相关，这一点可通过条件性疼痛调制（conditioned pain modulation）减弱得到证实，且此类改变可能由前额叶功能（frontal functioning）差异介导。然而，目前对于认知疼痛调控（cognitive pain modulation）中潜在的年龄相关改变——例如疼痛分心——尚不清楚。
在第一轮实验中，30名健康青年成年人（19~35岁）与30名健康老年成年人（59~82岁）完成了一套神经心理学测试（neuropsychological tests）。第二轮实验中，我们采集了受试者的功能性脑成像（functional brain images）数据；此时受试者需完成一项包含两种认知负荷（cognitive load）水平（高负荷vs.低负荷）的工作记忆任务（working memory task），同时接受个体化调整的热刺激（heat stimuli）（温热刺激vs.痛觉刺激）。
在两个年龄组中，完成高负荷任务均与痛觉刺激的感知强度与不适感显著降低，以及疼痛加工（pain processing）相关脑区激活减弱相关。组间比较显示，与老年组相比，青年组在高负荷任务相较于低负荷任务时，疼痛加工相关脑区——例如右侧脑岛（insula）、右侧扣带回中部（mid cingulate cortex）以及左侧缘上回（supramarginal gyrus）——的去激活程度更强。另一方面，与青年组相比，老年组在高负荷任务相较于低负荷任务时，前扣带回皮层（anterior cingulate cortex）的激活程度更高。
协变量分析（covariate analyses）显示，执行功能（executive functions）可显著预测老年群体的神经疼痛调控：在高负荷任务相较于低负荷任务时，执行功能越好的老年受试者，其脑岛（insula）、丘脑（thalamus）与初级躯体感觉皮层（primary somatosensory cortex）的去激活程度越显著，且前额叶脑区（prefrontal regions）的激活程度越高。本研究结果表明，老年群体的认知疼痛调控存在改变，且执行功能的保留或许可改善疼痛分心的干预效果。