LAUSR

OBJECTIVE In this study, we compared two working memory conditions to study the analgesic effect of a distraction in elderly versus young people and the effect of pain on performance on the distracting task. METHODS Twenty-seven young and 34 old subjects performed 1- and 2-Back working memory tasks, representing low and high cognitive loads, respectively. Infrequent, brief hot nociceptive and cold non-nociceptive stimulations were delivered 100 ms prior to visual N-Back stimuli. Contact heat and cold evoked potentials were analyzed in the absence of cognitive tasks and during the N-Back tasks. We compared the pain and cold intensity ratings and reaction times in trials preceded by nociceptive and cold stimulations and in trials not preceded by thermal stimulations between groups and between N-Back conditions. RESULTS In both groups, performing the 1- and 2-Back working memory tasks reduced the perceived intensity of nociceptive and cold stimuli. In elderly subjects performing 2-Back memory tasks, response times to trials following nociceptive stimulation were longer than to trials following cold or non-stimulation. By contrast, thermal stimulations had no effect on reaction times in young subjects. The amplitude of the N2P2 component was lower in the old compared to the young group in the absence of cognitive task. In the old group, N-Back tasks had no effect on the N2P2 amplitude, whereas it reduced N2P2 amplitude in the young. CONCLUSION Distraction analgesia is preserved in elderly subjects. However, this successful pain modulation seems to be accompanied by performance costs in the distracting tasks.