Volumetric brain correlates of gait associated with cognitive decline in community-dwelling older adults

Abstract

Objective: To determine the extent to which the regional brain volumes associated with slow gait speed can inform subsequent cognitive decline in older adults from the Rush Memory and Aging Project.

Approach: We utilized deformation-based morphometry (DBM) in a whole-brain exploratory approach to identify the regional brain volumes associated with gait speed assessed over a short distance during an in-home assessment. We created deformation scores to summarize the gait-associated regions and entered the scores into a series of longitudinal mixed effects models to determine the extent to which deformation predicted change in cognition over time, controlling for associations between gait and cognition.

Results: In 438 older adults (81 ± 7; 76% female), DBM revealed that slower gait speed was associated with smaller volumes across frontal white matter, temporal grey matter, and subcortical areas and larger volumes in the ventricles during the same testing cycle. When a subset was followed over multiple (5 ± 2) years, slower gait speed was also associated with annual declines in global cognition, executive functioning, and memory abilities. Several of the gait-related brain structures were associated with these declines in cognition; however, larger ventricles and smaller medial temporal lobe volumes proved most robust and attenuated the association between slow gait and cognitive decline.

Conclusion: Regional brain volumes in the ventricles and temporal lobe associated with both slow gait speed and faster cognitive decline have potential to improve risk stratification for cognitive decline in older adults.

Keywords: MRI; attention; brain volumes; cognitive decline; executive functioning; gait speed; memory; older adults.

Figure 1

Regional deformation patterns associated with gait speed, as assigned to four PCA factor-derived deformation scores: (A) contraction (i.e., larger volumes) in the medial temporal lobe and thalamus with expansion (i.e., smaller volume) of the ventricles (i.e., PC #1) to the MIITRA template; (B) contraction across the left anterior cingulate, right middle frontal gyrus and insula, and the genu and splenium of the CC (i.e., PC #2); (C) contraction across the left and right anterolateral temporal lobes (i.e., PC #3); and (D) contraction across the left and right insula (i.e., PC #4).