Predictors of Usual Gait Speed in Persons with Mild‐Moderate Alzheimer’s Dementia

Abstract

AbstractBackgroundGait speed, the time needed to walk a specified distance at normal pace, is a strong predictor of adverse outcomes. Usual gait speed ≥1.0 meters/second (m/s) is associated with better survival in community‐dwelling older adults. The purpose of this cross‐sectional study was to 1) evaluate usual gait speed and their predictors in community‐dwelling older adults with mild‐to‐moderate Alzheimer’s dementia (AD) participating in a pilot study investigating the effects of aerobic exercise on cognitive function.MethodUsual gait speed was calculated from the 4‐meter walk test (4mWT) (part of the short physical performance battery test [SPPB] according to published guidelines. Potential predictors were selected based on the literature and included: demographics (age, sex, cognition [Mini‐Mental State Examination (MMSE) score], body mass index [BMI], balance (balance score from SPPB), aerobic fitness (peak oxygen consumption [VO2peak] from cycling‐based cardiopulmonary exercise test and walking distance from shuttle walk test [SWT]), and muscle strength/power (repeated chair rise test [RCR] of the SPPB). Data were analyzed using descriptive statistics (means/SD) and multiple linear regression.ResultThe sample (n = 90) averaged 76.9±6.6 years old, 44% female, 21.71±6.6 MMSE, and 24.6±11.2 BMI. Usual gait speed was 0.96±0.24 m/s, with 61% having a usual gait speed ≥1.0 m/s. Regression analysis showed that aerobic fitness (SWT distance) and muscular strength/power (RCR) were significant predictors of usual gait speed. Specifically, 45% of the variability in usual gait speed was accounted for by aerobic fitness (SWT distance) and muscle strength/power (RCR) (R2 = 0.449; SEE = 0.175; p≤0.001). In the subset with usual gait speed <1.0 m/s (n = 45), seventy‐three percent of the variability in usual gait speed was accounted for by aerobic fitness (SWT distance and VO2peak) and muscle strength (RCR) (R2 = 0.728; SEE = 0.07; p≤0.001).ConclusionOur findings suggest that aerobic fitness and muscular strength/power are significant determinants of usual gait speed in community‐dwelling older adults with mild‐to‐moderate AD and particularly in persons usual gait speed <1.0 m/s. Exercise interventions that have the capacity to enhance aerobic fitness and muscular strength/power will be important in preventing adverse outcomes associated with reduced usual gait speed in persons with AD.