Constricting Life Space and Likelihood of Neurodegenerative Disease in Community-Dwelling Older Men

IMPORTANCE: Life space is a measure of the frequency, range, and independence of movement through the environment. There is increasing interest in life space as a holistic measure of function in older adults, but the association between change in life space and incident neurodegenerative disease is unknown. OBJECTIVE: To evaluate the association between change in life space and cognitive decline or incident neurodegenerative disease over 7 years among community-dwelling older men. DESIGN, SETTING, AND PARTICIPANTS: In this cohort study, logistic regression analyses were used to examine the association of baseline and change in life space with change in cognition unadjusted and adjusted for demographics, cardiovascular risk factors, depression, gait speed, and physical activity. Mixed linear effects models were used to evaluate the association between change in life space and change in cognition. Men were recruited from 6 US sites to participate in a prospective, community-based cohort study of aging and followed-up from 2007 to 2014. Individuals with prevalent dementia or Parkinson disease (PD) at baseline were excluded. Data were analyzed from May 2022 to September 2023. EXPOSURE: Life space, assessed using the University of Alabama at Birmingham Life Space Assessment and divided into tertiles. MAIN OUTCOMES AND MEASURES: Participants completed the Modified Mini-Mental State (3MS) Test, and Trail-Making Test Part B at baseline and 7 years later. At follow-up, participants were asked about a new physician diagnosis of dementia and PD. RESULTS: A total of 1684 men (mean [SD] age, 77.1 [4.2] years) were recruited and over 7 years of follow-up, 80 men (4.8%) developed dementia and 23 men (1.4%) developed PD. Mean (SD) life space score was 92.9 (18.7) points and mean (SD) change was −9.9 (22.3) points over follow up. In the adjusted model, each 1-SD decrement in life space was associated with increased odds of dementia (odds ratio [OR], 1.59; 95% CI, 1.28-1.98) but not PD (OR, 1.48; 95% CI, 0.97-2.25). For each 1-SD decrement in life space, men worsened by 20.6 (95% CI, 19.8-21.1) seconds in their Trails B score (P < .001) and declined by 1.2 (95% CI, 1.0-1.3) points in their 3MS score (P < .001) over 7 years. CONCLUSIONS AND RELEVANCE: In this study of 1684 men followed up over 7 years, change in life space was associated with faster cognitive decline and increased likelihood of neurodegenerative illness. Future studies should examine the role of clinician assessments or wearable electronics in tracking life space in older adults at risk of cognitive decline and neurodegenerative illness.