Pain-Related Evoked Potentials in Older Adults with Chronic Pain: A Cross-Sectional study.

Background: Chronic pain and aging trigger different plastic changes in pain processing, however, their combined effects on electroencephalographic correlates remain unexplored. This study aimed to examine these neural processing alterations in older adults with chronic pain, comparing them with pain-free older and younger adults.

Methods: We compared pain-related evoked potentials (Pain ERPs) of 26 older adults with chronic pain (69,15 ± 4.63 years; 11 males), 26 pain-free older participants (69,65 ± 4.08 years; 12 males) and 27 pain-free younger adults (21,37 ± 1.92 years; 14 males). Participants received 30 painful and 30 non-painful electrical stimuli to the dorsum of the non-dominant hand individually calibrated using intra-epidermal electrical stimulation (IES) delivered via a concentric needle WASP electrode. EEG data were analysed using cluster-based permutation test.

Results: Older participants with chronic pain showed enhanced pain ERPs from 150 to 500 ms in comparison to healthy older adults. Younger adults showed higher amplitudes than both older participants' groups except in late potentials (350-500 ms). No differences between younger and older adults with chronic pain were found.

Conclusions: : We found a similar amplitude reduction in early (linked to sensory processing), but increased amplitude in late (linked to evaluative and attentional mechanisms) evoked potentials to pain in older adults with chronic pain in contrast to pain-free older adults. This pattern may reflect an age-related sensory coding decline combined with chronic pain-related enhancement of affective-attentional processing. Altogether suggest that plastic changes driven by suffering from long-lasting pain outweigh those resulting from the normal aging process when both coexist.