Pupil–galvanic Skin Response Synchrony during Family-centered Visual Reminiscence in Older Adults with Cognitive Impairment: A Proof-of-concept Study

Introduction: Subtle changes in attention and emotion characterize early cognitive decline. In Asian elders, where family is central, culturally tailored reminiscence therapy (RT)-inspired visual stimulation may amplify autobiographical engagement. We aimed to determine whether visual–autonomic coupling, assessed through eye-tracking and galvanic skin response (GSR), serves as a sensitive physiological indicator of cognitive vulnerability during family-centered, RT-inspired visual stimulation. Methods: This cross-sectional study enrolled 37 older adults (aged 54–92) from dementia service centers in Taiwan, stratified by clinical dementia rating (CDR) score (0, 0.5, 1). Participants viewed self-selected community and family-centered personal photos (early, ≥30 years; recent, <5 years), whereas eye-tracking and GSR were simultaneously recorded to assess visual–autonomic synchrony. Results: The normal cognition group (CDR = 0) showed significantly larger pupil diameters, especially for recent personal photos (3.56 ± 0.87 mm), compared to CDR = 0.5 (2.64 ± 0.52 mm) and CDR = 1 (2.97 ± 0.61 mm; P < 0.05). GSR responses exhibited sharper declines in CDR = 0.5 and blunted patterns in CDR = 1. Visual–autonomic coupling strength differed by stage: moderate in CDR = 0 ( r = 0.41–0.47), stronger in CDR = 0.5 ( r = 0.62–0.71), and minimal in CDR = 1 ( r = 0.14). Time-resolved peaks reached ρ ≈0.90 in CDR = 0. Notably, high responders showed detectable synchrony to self-relevant stimuli, suggesting residual plasticity. Conclusion: These findings indicate that pupil–GSR coupling could serve as an exploratory indicator of early cognitive vulnerability. The study supports the potential of personalized, RT-inspired visual stimulation for guiding interventions in individuals at risk of dementia.