JMIR Publications

ABSTRACT

Background:

The transition from acute to chronic pain often reflects a persistent dissociation between physical tissue damage and subjective reports. In alignment with the 2020 International Association for the Study of Pain (IASP) definition, pain is a personal experience filtered through a latent "susceptibility architecture." While clinical assessment currently relies on static, text-based questionnaires, these are often confounded by linguistic interpretation bias and cognitive literacy. We hypothesized that an individual’s internal psychological substrate—traditionally captured via text—can be characterized through real-time behavioral signatures during physical challenge.

Objective:

This study aimed to demonstrate that the "pain-prone" phenotype can be identified through high-frequency digital assessment of pain ratings. By correlating established psychometric traits with dynamic behavioral signatures, we sought to establish a foundation for "Digital Phenotyping" that moves beyond the limitations of linguistic self-reports.

Methods:

A cohort of 534 healthy volunteers (mean age 38.6 years; 336 males, 198 females) underwent a controlled thermal stimulation protocol (36 °C, 44 °C, 46 °C, and 48 °C). Continuous pain intensity was recorded via a high-frequency (1000 Hz) digital Visual Analog Scale (VAS). To establish a psychological baseline, participants were profiled using the Revised NEO Personality Inventory (NEO-PI-R) and the Relationship Questionnaire (RQ). Two behavioral indices were then derived from the digital VAS: the Temporal Augmentation Index (TAI), reflecting within-stimulus physiological sensitization, and the Cognitive Contrast Effect, reflecting evaluative stability relative to preceding sensory contexts.

Results:

Repeated measures multivariate analysis of variance (MANOVA) confirmed a highly significant main effect of time for all noxious conditions (P<.001; for 46 °C, t533=27.69). Perceived intensity at 46 °C was significantly lower following 48 °C (mean VAS 12.31, SE 0.67) than 36 °C (mean VAS 30.45, SE 0.97; t533=–25.76, P<.001). Crucially, these behavioral signatures significantly correlated with the questionnaire-based profiles: Vulnerability (N6) was positively associated with both TAI (P=.02) and contrast magnitude (P=.002), whereas Self-Discipline (C5) showed negative associations (TAI: P=.01; contrast: P=.03). Mediation analysis identified two distinct pathways: (1) a "Stabilization Path," where Secure Attachment fully mediated the inhibitory effect of C5 on evaluative instability (direct effect c'=–0.25, P=.11), and (2) an "Instability Path," where N6 exerted a direct amplifying effect on instability (c'=0.34, P=.03).

Conclusions:

Subjective pain evaluation is governed by a stable internal psychological substrate. By shifting the assessment modality from linguistic self-reports to dynamic behavioral signatures, we provide a framework for "Digital Phenotyping." These evaluation patterns serve as a "Digital Stethoscope" for the mind, enabling the identification of latent susceptibility before chronification and offering a novel foundation for personalized precision pain management. Clinical Trial: Japan Registry of Clinical Trials identifier, jRCT1090220286; https://jrct.mhlw.go.jp/en-latest-detail/jRCT1090220286