Sensory reweighting patterns and fall history in early geriatric age: implications for physiotherapy assessment

Abstract

Background: Falls are a leading cause of injury and functional decline among older adults. Although fall rates increase with advanced age, early alterations in postural control may already be present in early geriatric age. Postural stability depends on dynamic sensory reweighting among visual, somatosensory, and vestibular inputs. Subtle impairments in this adaptive process may not be detected during routine quiet standing under stable conditions. This study aims to investigate sensory reweighting indices based on center of pressure (CoP) sway area under four standardized sensory conditions and determine their ability to discriminate fall history in early geriatric age. Methods: This secondary cross-sectional analysis included 34 adults aged 60–70 years (9 fallers, 25 non-fallers). Postural sway was recorded during quiet standing under four conditions: firm surface eyes open (Firm-EO), firm eyes closed (Firm-EC), foam eyes open (Foam-EO), and foam eyes closed (Foam-EC). Three indices were calculated: Visual Dependency Index (VDI), Somatosensory Vulnerability Index (SVI), and Postural Adaptability Index (PAI). Between-group differences were assessed using the Mann–Whitney U test. Logistic regression and receiver operating characteristic (ROC) analyses were performed to explore associations and discriminative performance. Results: Fallers demonstrated significantly higher PAI values than non-fallers (P = 0.024), indicating reduced adaptability under escalating sensory challenge. SVI under eyes-closed conditions approached significance (P = 0.055). ROC analysis showed acceptable discrimination for PAI (AUC = 0.756, 95% CI 0.569–0.942, P = 0.007) and SVI_EC (AUC = 0.720, P = 0.011). Logistic regression revealed a positive, though non-significant, association between PAI and fall history (OR = 1.13, P = 0.075). Conclusions: Early geriatric age with fall history exhibit impaired postural adaptability under multisensory challenge. Sensory-derived adaptability indices may provide additional insight beyond absolute sway magnitude and support early identification of fall vulnerability. However, their role in fall risk identification requires further validation.