Age does not affect sex effect of conditioned pain modulation of pressure and thermal pain across 2 conditioning stimuli

Abstract

Introduction: Conditioned pain modulation (CPM) is a laboratory test resulting in pain inhibition through activation of descending inhibitory mechanisms. Older adults consistently demonstrate reduced CPM compared with younger samples; however, studies of sex differences in younger cohorts have shown mixed results. Objectives: This study tested for sex differences in CPM within samples of younger and older adults. Methods: Participants were 67 younger adults (mean age = 25.4 years) and 50 older adults (66.4 years). Study conditioning paradigms were the cold-pressor test and contact heat pain administered in separate sessions. Pressure pain threshold and ramping suprathreshold heat were the test stimuli across three time points after presentation of the conditioning stimuli (CS). Results: Significant inhibition was observed during both testing sessions. The hypothesis for sex differences across both age cohorts was supported only for ∆PPTh. However, sex differences did not reach significance for either paradigm using ascending suprathreshold heat as the test stimuli. The overall trend was that younger males experienced the strongest CPM and older females the weakest. From a methodological perspective, duration differences were seen in CPM, with inhibition decaying more quickly for PPTh than for suprathreshold heat pain. Furthermore, there were no differences in inhibition induced by cold-pressor test and contact heat pain as CS. Conclusion: Sex differences were similar across both age cohorts with males experiencing greater inhibition than females. Cross-sectional associations were also demonstrated between CPM inhibition and measures of recent pain, further supporting CPM as an experimental model with clinical utility.

Comparison of five conditioned pain modulation paradigms and influencing personal factors in healthy adults

“…Age only had influence on CPM at the m. trapezius with the CPA as conditioning stimulus, however, the age range in the present study was relatively small, and the mean age indicated a rather young sample. The weakest CPM‐effect was found in older females (Riley et al., 2020). In the current study there were only six participants (four women) above 40 years, which explains the limited influence of age.…”

Phenotyping peripheral neuropathic pain in male and female adolescents: pain descriptors, somatosensory profiles, conditioned pain modulation, and child–parent reported disability

“…Average pain last week (0-10 NRS) Total score 7 [7,8] 19 [13,23] 7.5 [6,9] 18 [12,24] 7 [7,8] 18 [13,19] 7 [7,8] 22 [19,24] McGill Pain Questionnaire Sensory (0-33) 15 [12,18.5] 15.5 [12,18.8] 14 [9,19] 15. 5 [13,17.3] Affective (0-12) 4 [2,6] 3.5 [1.3,5] 4 [2,6] 4 [3,6] [4,19] n=19 25 [18,40] n=19 42 [27,56] n=13 14 [3,16] 31 [18,36] Data presented as mean±SD, (%), median [IQR 25 th , 75 th percentile], or n (%).…”

The Potential Clinical Utility of Pressure-Based vs. Heat-Based Paradigms to Measure Conditioned Pain Modulation in Healthy Individuals and Those With Chronic Pain

“…Although the proportion of males and females in our study was not significantly different between groups, the healthy group was significantly younger than the chronic pain group. Interestingly, a recent study in healthy individuals found the age effect was larger than the sex effect; across all the different stimulus modality paradigms younger males had the strongest inhibitory CPM ( 32 ). This aligns with previous findings showing that younger and healthy individuals on average have a stronger inhibitory CPM than older individuals and those with chronic pain ( 13 ).…”