Association of motor function with cognitive trajectories, risk of mild cognitive impairment, and structural brain differences

Abstract

AbstractBackgroundThe impact of motor function (MF) on cognitive trajectories and mild cognitive impairment (MCI) remains unclear. This study aimed to examine the association of MF with cognitive trajectories, risk of MCI, and structural brain differences on magnetic resonance imaging (MRI).MethodWithin the Rush Memory and Aging Project, 1,216 cognitively intact participants (mean age: 78.60±7.25 years) were followed for up to 22 years. Baseline global MF was assessed by averaging the z‐scores of 10 motor tests and categorizing these scores tertiles (low middle, and high). Global and domain‐specific cognitive functions – including episodic memory, semantic memory, working memory, visuospatial ability, and perceptual speed – were assessed annually through 19 cognitive tests. Incident MCI was detected and diagnosed based on standard criteria. A subsample (n = 284) underwent brain MRI and regional structural brain volumes were measured. Data were analyzed using linear mixed‐effects models, Cox regression, and linear regression.ResultAt baseline, global MF scores ranged from 0.46 to 1.82 (mean score: 1.06 ± 0.22). During the follow‐up (median, 6.98 years; interquartile range, 3.08‐10.75 years), 553 participants (45.48%) developed MCI. Compared to participants with high MF, those with low MF had faster decline in global cognition (β = ‐0.05, 95% confidence interval [CI]: ‐0.06 to ‐0.03), episodic memory (β = ‐0.05, 95% CI: ‐0.07 to ‐0.03), semantic memory (β = ‐0.04, 95% CI: ‐0.05 to ‐0.02), working memory (β = ‐0.04, 95% CI: ‐0.05 to ‐0.03), visuospatial ability (β = ‐0.03, 95% CI: ‐0.04 to ‐0.02), and perceptual speed (β = ‐0.04, 95% CI: ‐0.06 to ‐0.03) over the follow‐up. The multi‐adjusted hazard ratio (95% CI) of MCI was 1.84 (1.41 to 2.42) for the lowest MF tertile compared to the highest. Furthermore, the low MF was related to a significantly greater volume of white matter hyperintensities (β = 0.16, 95% CI: 0.01 to 0.32), but not total brain, white matter, or gray matter volumes (all P >0.05).ConclusionLow MF is associated with faster cognitive decline (including episodic memory, semantic memory, working memory, visuospatial ability, and perceptual speed) and a moderately increased risk of MCI. Vascular pathologies might play an important role in the MF‐MCI association.