Relationship of Alzheimer's Disease and Related Dementias Plasma Biomarkers With Mobility in Cognitively Unimpaired Older Adults

BACKGROUND: Temporal relationships between physical and cognitive decline with aging are poorly understood, and little is known about the underlying mechanisms linking these conditions. We hypothesized that plasma biomarkers of Alzheimer's disease and related dementias may be associated with mobility performance in older adults who are cognitively unimpaired. METHODS: We constructed separate linear mixed models to examine the cross-sectional associations of 5 plasma Alzheimer's disease and related dementias and aging-related biomarkers with 4 measures of mobility in a cohort of 192 cognitively unimpaired older adults. We secondarily described the association of the same biomarkers with 4 cognitive domain scores. RESULTS: Higher phorphorylated-tau181 was associated with worse performance on the expanded short physical performance battery, slower 4 m gait speed, and shorter balance time. Higher neurofilament light was associated with worse expanded short physical performance battery, slower 4 m gait speed, and slower 400 m gait speed in adjusted models. However, there was no association of Aβ42/Aβ40, p-tau217, or glial fibrillary acidic protein with mobility. Only p-tau217 was associated with global and processing speed cognitive domain scores in multivariable models, but not after adjusting for multiple comparisons. CONCLUSIONS: These data suggest that p-tau181 and neurofilament light are potential markers of mobility performance in cognitively normal older adults, even when they are not associated with cognitive performance. Future studies should examine how such markers predict change over time in mobility and cognitive function and whether they may indicate pathways that could be targeted for preventive management.