671: Autonomic Reactivity and Personality Traits Predict Offset Analgesia Efficacy

Topic: Experimental (Non-clinical) Human Studies
Subtopic: Non -specific to any diagnosis, Psychology, Pain mechanisms (e.g. descending inhibitory control, placebo, inflammation), Quantitative Sensory testing (static and dynamic, e.g., HPT, PPT, CPM, TSP, offset analgesia)

Background and Aims: Offset Analgesia (OA) exhibits significant individual variability, yet the underlying mechanisms remain unclear. This study examined whether autonomic reactivity during nociception and specific personality facets predict analgesic efficacy in healthy volunteers.

Methods: Sixty-four healthy volunteers (28.2±6.8 years) underwent thermal stimulation (baseline 36.0°C, peak 48.9°C; two-peak program) using a TSA2 (Medoc, Israel). Continuous blood pressure was recorded using a ViewPhii (Miyuki Giken, Japan), and pain intensity was assessed via VAS. ΔOA was defined as the normalized difference between peak VAS and the minimum VAS within 10 seconds after peak offset. Autonomic reactivity was the BP difference between 38–40°C and peak. Top/bottom 33% (n=21 each) were stratified into High/Low groups based on 1) ΔOA magnitude and 2) autonomic reactivity. Analyzed via t-tests, Chi-square, and stratified Spearman correlations.

Results: Chi-square revealed a significant association between ΔOA and BP groups (p=0.049). High ΔOA responders exhibited higher N2 (Angry hostility) but lower total Agreeableness, A3 (Altruism), A4 (Compliance), A6 (Tender-mindedness), O2 (Aesthetics), and O6 (Values) (p<0.05). High-BP group showed significantly higher N3 (Depression) (p=0.049). Stratified correlations revealed that in High responders, ΔOA correlated with low Anxiety (N1), Depression (N3), and Vulnerability (N6), and high Activity (E4) (p<0.05). In Low responders, Compliance (A4) strongly hindered ΔOA (ρ=-0.70, p<0.001). Additionally, High responders' BP reactivity positively correlated with N, N1, N4, N6, and A3; Low responders correlated negatively with C1 (p<0.05).

Conclusions: Endogenous pain modulation is significantly shaped by the interplay between autonomic reactivity and personality facets. High analgesic efficacy is driven by emotional stability and energetic engagement, whereas excessive Compliance (suppression of aggression) acts as a critical inhibitor. Furthermore, a "guarded" personality (low Values and Straightforwardness) may serve as a protective strategy to compensate for physiological autonomic vulnerability. These psychophysiological profiles offer a refined framework for identifying individual differences in pain modulation and personalized pain management.

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Presenting Author: Chie Kishimoto
Submitting Author: Chie kishimoto

Senior Author: Aya Nakae

IASP 2026 Global Year theme of Neuropathic Pain: No

• Hani M. Bu-Omer: PhD - Advanced Telecommunications Research Institute International
• Aya Nakae: MD, PhD - Advanced Telecommunications Research Institute International