Eye movement features are associated with cognitive and mobility decline

BackgroundEye movement is a vital indicator of neurodegenerative diseases, brain health, and behavior. However, existing knowledge is limited to patient populations or cross-sectional samples. Little is known about eye movement in association with longitudinal cognitive and mobility decline in aging.ObjectiveInvestigate relationships between eye movement features with cognitive impairment, including Alzheimer's disease (AD), and longitudinal decline in cognition and mobility.MethodsIn 543 Baltimore Longitudinal Study of Aging participants (mean age = 71 years), we examined associations of eye movements with cognitive impairment of any severity, vascular conditions, and falls using logistic regression, and up to 18-year longitudinal changes in cognition and mobility using linear mixed-effects models. Four eye movement features (saccade, smooth pursuit, vergence, optokinetic nystagmus) were derived from a portable eye-tracking perimeter (Neurolign Dx100) using machine learning Least Absolute Shrinkage Selection Operator regression.ResultsHigher saccade, smooth pursuit, and vergence were bivariately or marginally associated with lower odds of cognitive impairment, including AD, and vascular diseases. In age- and sex-adjusted models, higher saccade was associated with slower declines in cognition (attention: Trail Making Test-Part A), mobility, and balance. Higher smooth pursuit was associated with slower decline in mobility and balance. Higher vergence was associated with slower cognitive decline (executive function: Trail Making Test-Part B; visuoperceptual speed: Digit Symbol Substitution Test). Higher optokinetic nystagmus was associated with lower odds of falls and slower decline in balance.ConclusionsSelect eye movement features may be indicators of age-related cognitive and mobility decline. Future studies are warranted to investigate underlying neuroimaging markers and brain pathology.