Contributors to Poor Mobility in Older Adults: Integrating White Matter Hyperintensities and Conditions Affecting Other Systems

Abstract

Background: Age-related mobility limitations are debilitating and common. Cerebral white matter hyperintensities (WMH) and conditions affecting other systems are known contributors, but have been studied in isolation.

Methods: In 2,703 adults aged 65 years or older, we assessed cross-sectional and longitudinal gait speed and mobility disability (self-reported difficulty walking half mile) in those with and without high burden of MRI-defined WMH along with six other conditions (OCs) affecting mobility: gender-specific weak grip; poor self-reported vision; gender-specific lowest quartile of forced vital capacity; self-reported joint pain; ankle-arm index less than 0.9; and body mass index (BMI) greater than 30 kg/m2. Separate regression models adjusted for age, gender, and race were repeated for each OC and based on a 4-level predictor: -WMH/-OC; -WMH/+OC; +WMH/-OC; and +WMH/+OC.

Results: Gait speed was fastest in those with -WMH/-OC and slowest for those with +WMH/+OC. Gait speed was similar for either WMH or one of the OC (p range: .07-.9), except for BMI. Those with a high BMI had slower gait speed than those with WMH (p = .01). Declines in gait speed over 6 years were similar for all groups. Results for both prevalent and incident mobility disability showed that associations for WMH and OC were similar for weak grip, poor vision, and low forced vital capacity (p range: .1-.7). Having joint pain, low ankle-arm index, or high BMI was associated with higher prevalent and incident mobility disability compared with having WMH (p range: <.001-.02).

Conclusions: Cerebral WMH should be considered along with conditions affecting mobility from other systems when considering risk and treatment for mobility limitations.

Keywords: Disability; Gait speed; Mobility; White matter hyperintensities.

Figure 1.

Estimated gait speed (m/s) by white matter hyperintensities (WMH) or other condition only (two middle lines (red and green lines online)), both (bottom line), or neither (top line) over 6 years of follow-up (n = 2,703). Results are for white women of mean age (74 years); relative differences were similar for other groups.

Figure 2.

Estimated cross-sectional proportion with mobility disability by white matter hyperintensities (WMH), other conditions (see x-axis), both, or neither (n = 2,703). Results are for white women of mean age (74 years); relative differences were similar for other groups.