Rising Energetic Cost Of Walking Predicts Cognitive Impairment

Purpose: The energetic cost of walking increases with age and is a physiological indicator of risk of physical function decline. Whether the energetic cost of walking is a physiological indicator of risk of cognitive decline is unknown. We investigated the longitudinal associations between the energetic cost of walking and cognitive impairment in adults aged ≥65 years participating in the Baltimore Longitudinal Study of Aging (BLSA). METHODS: A total of 721 cognitively unimpaired adults at baseline (mean age 74.1 ± 7.2 years, 52% women) completed walking energy expenditure assessments with metabolic measurement (V̇O2) and clinical cognitive testing over a 4.7 ± 3.8 year follow-up period. Linear mixed effects and Cox proportional hazard regression models adjusted for age, sex, education, APOE ε4 status, and comorbid conditions tested the associations between: 1) energetic cost of walking trajectories among older adults who progressed to cognitive impairment vs those who did not, and 2) baseline energetic cost of walking and progression to cognitive impairment. RESULTS: Among 721 participants, 99 progressed to cognitive impairment, including dementia (14%). Those who progressed had a steeper increase in the energetic cost of walking than non-progressors (B = 0.10; p = .011; Figure 1). Baseline energetic cost of walking was not associated with progression to cognitive impairment among those aged 65-74 (HR = 0.89,CI = 0.78-1.02,p = 0.084), however, among those aged ≥75 a higher energetic cost of walking was associated with increased risk (HR = 1.1, CI = 1.03-1.18, p = 0.007; Figure 2). CONCLUSION: Different energetic trajectories were observed between participants who progressed versus did not progress to cognitive impairment, with those having a higher energetic cost of walking having greater risk. Preserving walking efficiency could be a key strategy for reducing cognitive decline, with the energetic cost of walking serving as a novel target for future interventions.Supported by: This research was supported by the Intramural Research Program of the National Institute on Aging of the National Institutes of Health. Data used in the analyses were obtained from the Baltimore Longitudinal Study of Aging, a study performed by the National Institute on Aging Intramural Research Program (blsa.nih.gov). Ryan J. Dougherty was supported by grant K01AG080122