Proxy measures of cognitive reserve and trajectories of gait and cognitive decline in older adults

Abstract

AbstractBackgroundLifestyle interventions are an emerging area of interest in dementia prevention. Education, physical activity, and social interactions are potentially modifiable lifestyle factors that are considered proxies of cognitive reserve. People with greater cognitive reserve could be protected against decline in gait and cognition, two interrelated problems associated with dementia, by coping better with age‐ or pathology‐related brain changes. We examined whether decline in gait and cognitive functions are different in those with higher versus lower levels of education, physical activity, and social interactions.MethodGait and cognitive performance in 1,095 LonGenity study participants (mean age = 75.4±6.7 years) that were free of dementia at baseline were examined up to 12 years. Gait speed was measured during usual pace (single‐task walking, STW‐speed) and walking‐while‐talking (WWT‐speed). Cognitive performance was measured with standard neuropsychological tests and a standardized composite global cognitive measure was derived. Years of education, number of blocks walked per day, living with someone and engaging in paid or volunteer work (markers of social interactions) were obtained from self‐report. Linear mixed‐effects models adjusted for sex, parental longevity, cognitive impairment, and global health were used to examine age‐associated changes in gait and cognition in those with and without greater cognitive reserve.ResultSTW‐speed and WWT‐speed did not vary as a function of education, physical activity, or social interactions. Greater number of blocks walked per day was associated with slower decline in global cognition, Trail Making Test (TMT)‐A, TMT‐interference, digit symbol substitution, logical memory, figure recall, free recall, category and phonemic fluency tests. Higher education was associated with slower decline in global cognition, TMT‐interference, TMT‐A and figure copy task. Living with someone was associated with slower decline in global cognition, digit symbol substitution and logical memory. Paid or volunteer work was associated slower decline in global cognition.ConclusionHaving higher education, more physical activity and social interactions appear to protect against cognitive, but not gait decline, potentially by building up cognitive reserve. The multifaceted etiology and relatively earlier decline of gait may render it less influenced by potentially modifiable risk factors in late life than cognition.