Abstract
BACKGROUND: Age-related changes in vestibular function may play a role in decreased postural control and increased fall risk. Past research suggests that age-related changes in vestibular perception begin at ~40 years of age; however, this pattern may vary depending on motion trajectory, reflecting contributions of peripheral end-organ structures. Further, motion specific relationships to sway variability have been previously identified. However, relationships between age-related vestibular perceptual changes to multiple sway metrics in multiple planes, reflecting unique aspects of postural control, have yet to be quantified. METHODS: 100 healthy adults (21-84 years) completed a vestibular threshold test battery and quiet stance balance assessments. All participants completed motion conditions with predominant contributions from the horizontal canals (2 Hz yaw rotation), vertical canals (2 Hz RALP/LARP tilt), utricles (1 Hz y-translation), saccules (1 Hz z-translation), and integration of canal-otolith cues (0.5 Hz roll tilt). For balance testing, participants completed an instrumented Modified Romberg Balance Test. Regression analyses assessed relationships between age-adjusted measures of vestibular perception to root mean square distance (RMS), mean velocity (MV), and mean frequency (MF) of center of pressure (CoP) in the mediolateral (ML) and anterior-posterior (AP) planes. RESULTS: Thresholds for most motions - except 0.5 Hz roll tilt - were matched by a two-segment model with stable values below ~40-50 years and linear increases thereafter. For balance conditions with predominant vestibular contributions (i.e., eyes-closed foam-surface), associations between ML RMS to thresholds with predominant contributions from the utricle (y-translation) and canal-otolith integration (roll tilt) were identified. No consistent associations between vestibular thresholds to MV and MF were identified. CONCLUSION: Across a population, we were able to confirm that vestibular perceptual thresholds are stable until around middle age after which linear increases in perceptual sensitivity are seen. Our findings linking ML RMS to vestibular perceptual metrics support past hypotheses that sensory noise, as quantified by vestibular thresholds, may contribute to sway variability.