(169) Comparison of Temporal Stability of Conditioned Pain Modulation and Temporal Summation of Pain in Healthy Older and Younger Adults

Abstract

The temporal stability (test-retest reliability) of temporal summation of pain (TS) and conditioned pain modulation (CPM) has yet to be established in healthy older adults. The current study intended to compare the temporal stability of TS and CPM in healthy older and younger adults, as well as investigate factors that might impact TS and CPM stability. In a test-retest study, 40 healthy older adults and 18 healthy younger adults completed two sessions of quantitative sensory testing within a 2-week period that included: 1) TS of heat pain, 2) TS of mechanical pain, 3) CPM with pressure pain thresholds (CPM-PPT) and suprathreshold heat pain (CPM-Heat) as test stimuli and a cold water bath as conditioning stimulus. During each session participants completed the pain catastrophizing scale and the State Trait Anxiety Scale – state version. The relative stability (Interclass correlation coefficients: ICCs) and intra-individual stability coefficients (ISC) were examined for each variable. Bivariate correlations examined the association of psychological variables and age with the ISCs of TS and CPM. Younger adults showed good to excellent stability for TS (ICC's: 0.64-0.89), except for mechanical TS on the hand (ICC: 0.34). Older adults showed moderate to good stability for TS (ICC's: 0.48-0.79). Stability of CPM-PPT was poor for younger and older adults, whereas stability of CPM-Heat was good for younger adults but poor for older adults. Correlational analyses indicated greater ISC's for CPM were associated with greater stability of the pre-test stimuli. State anxiety was significantly associated with stability of CPM-Heat and TS. These findings suggest that 1) TS and CPM may be more reliable in younger compared to older adults and 2) state anxiety is an important factor influencing the stability of CPM and TS in healthy adults. This study was funded by the IUPUI Developing Diverse Researchers with Investigative Experience Grant.