Gray Matter Regions Associated With Functional Mobility in Community-Dwelling Older Adults.

Background/objectives: Neuroimaging indicators of reduced brain health in the form of lower gray matter volume (GMV), lower fractional anisotropy (FA), and higher white matter hyperintensity volume (WMHV) have been related to global mobility measures, such as gait speed, in older adults. The purpose was to identify associations between brain regions and specific mobility functions to provide a greater understanding of the contribution of the central nervous system to independent living.

Design: Cross-sectional study.

Setting: Research laboratory.

Participants: Seventy community-ambulating healthy older adults (mean age = 76 ± 5 years).

Measurements: Participants performed the following tests: gait speed, Five Times Sit to Stand, Four Square Step Test (FSST), and Dynamic Gait Index (DGI). Structural magnetic resonance imaging of each participant's brain was collected. Measures of regional GMV, tract-specific WMHV, and FA were extracted. Correlational analyses between the mobility measures and neuroimaging measures were conducted using whole brain and regional and tract-specific measures. This was followed by linear regression models relating the mobility measures to regions or tracts identified in the correlation analysis, and adjusting for age, sex, and body mass index.

Results: Significant associations were found between higher GMV in multiple regions, primarily the parietal and temporal lobes, and better performance in gait speed, DGI, and FSST. After adjusting for personal factors, greater parahippocampus GMV was independently associated with greater gait speed. Greater inferior parietal lobe, supramarginal gyrus, and superior temporal gyrus GMVs were associated with gait function. Greater postcentral gyrus, parahippocampus, and superior temporal gyrus GMVs were associated with faster FSST performance. The WMHV and FA were not significantly correlated with the mobility measures.

Conclusions: Gray matter regions associated with higher performance in mobility measures serving gait function and multidirectional stepping were those structures related to vestibular sensation, spatial navigation, and somatosensation. J Am Geriatr Soc 68:1023-1028, 2020.