Abstract
BackgroundThe ageing process is characterized by declines in physical and cognitive function. However, the relationship between these trajectories remains a topic of investigation.MethodsUsing four data waves collected triennially between ages 70 and 79, we tested for associations between multiple cognitive ability domains (verbal memory, processing speed, and visuospatial ability) and physical functions (walking speed, grip strength, and lung function). We first tested for associations between linear declines in physical and cognitive functions over the entire 9-year study period, and then, for lead-lag coupling effects between 3-year changes in cognitive and physical functions.ResultsSteeper linear decline in walking speed was moderately correlated with steeper linear declines in each cognitive domain. Steeper linear decline in grip strength was moderately correlated with steeper linear declines in verbal memory and processing speed. Lead-lag coupling models showed that decline in verbal memory was preceded by declines in walking speed and grip strength. By contrast, decline in grip strength was preceded by declines in processing speed and visuospatial ability, and decline in walking speed was preceded by decline in visuospatial ability. Following additional adjustment for covariates, only coupling effects from earlier decline in processing speed to later decline in grip strength remained significant (β = 0.545, p = .006).ConclusionOur findings provide further evidence of an association between cognitive and physical declines and point to the potential order in which these changes occur. Decline in processing speed in particular may serve as a unique early marker of declining upper body strength.
Highlights
The ageing process is characterised by declines in the mean levels of physical and cognitive function
The current study adopted the former CHC approach. d Whereas crystallised ability remains relatively stable in its mean level throughout much of adult life, te other cognitive domains tend to decline in mean level with age; processing speed follows a steady p trajectory of decline originating in early adulthood; visuospatial and memory abilities typically start e to decline in middle age [3,4]
We examined the relationship between parallel and dynamic time-ordered changes in physical and cognitive functions across the eighth decade of life
Summary
The ageing process is characterised by declines in the mean levels of physical and cognitive function. Whereas CHC theory is typically applied to the study of cognitive abilities in large non-pathological samples, executive function. D Whereas crystallised ability remains relatively stable in its mean level throughout much of adult life, te other cognitive domains tend to decline in mean level with age; processing speed follows a steady p trajectory of decline originating in early adulthood; visuospatial and memory abilities typically start e to decline in middle age [3,4]. Like memory and visuospatial ability, these physical functions, on average, peak in early adult life, begin to decline in midlife, and continue to decline in older age [5,6]. Declining cognitive and physical function is a near universal experience in older age, there is substantial variation between people in terms of levels of cognitive and physical function and their rates of decline with ageing [7,8]
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