Change in life space is associated with cognitive decline and increased risk of incident Alzheimer’s and Parkinson’s disease in older men

Abstract

AbstractBackgroundLife space measures the range of geospatial movement through one’s environment during daily functioning. Prior studies on the association of life space and cognitive change are mostly cross‐sectional and have mixed results. To clarify this association, we prospectively evaluated change in life space with cognitive decline and incident Alzheimer’s disease (AD) and Parkinson’s disease (PD).MethodWe studied 1,684 men enrolled in a prospective study of aging. We excluded individuals with probable dementia or PD at baseline (Study Year 7). Life space was evaluated with the self‐reported University of Alabama at Birmingham Life Space Assessment at Year 7 and Year 14. The composite life space score ranges from 0 (most restricted) to 120 (least restricted). Incident AD or PD was defined as a self‐reported physician diagnosis or medication use at Year 14. We conducted logistic regression analyses examining change in life space with the odds of our outcomes unadjusted and adjusted for age, clinic site, race, education, living arrangement, vascular risk factors, and depression. We also conducted mixed linear effects models to evaluate the association between change in life space and change in 3MS and Trails B score.ResultOf 1,684 men (mean age 77.1 +/‐ 18.7 SD) in our analytic cohort, 80 (4.8%) developed incident AD and 23 (1.4%) developed PD over 7 years. The mean (SD) life space score at baseline was 92.9 (18.7) and change over 7 years was ‐9.9 (22.3). In the fully adjusted model, each 1 SD decrement in life space was associated with increased odds of AD (OR 1.6, 95% CI 1.3, 2.0) and PD (OR 1.6, 95% CI 1.1, 2.5). For each 1 SD decline in life space, men worsened by 20.6 seconds in their Trails B score and 1.15 points in their 3MS score over 7 years (p<0.001 for both).ConclusionIn this novel longitudinal analysis, decline in life space is associated with cognitive decline and incident AD and PD. Future studies should examine whether decline in life space is a sensitive and practical way to identify older individuals at risk for cognitive dysfunction and neurodegenerative disease.