β-amyloid deposition is associated with gait variability in usual aging.
BACKGROUND
Higher amyloid burden predicts gait slowing in aging. Whether and which gait characteristics are associated with amyloid burden is less clear. Gait variability may be more sensitive to amyloid burden than mean gait characteristics.


METHODS
In the Baltimore Longitudinal Study of Aging, 99 older participants without neurological disease had concurrent amyloid imaging and assessment of gait characteristics. β-amyloid burden was measured using 11C-Pittsburgh compound B (PiB) positron emission tomography. PiB+/- status was based on a mean cortical distribution volume ratio (DVR) cut point. Gait characteristics were quantified by 3D motion analysis. Cross-sectional associations of PiB+/- status and DVR in motor-related regions (primary motor cortex, putamen, caudate) with gait characteristics were examined using linear regression, adjusted for age, sex, height, body mass index, gait speed and covariates (memory, executive function, visuoperceptual speed, depressive symptoms, cardiovascular risk, ApoE ε4, cerebrovascular burden, neurodegeneration, peripheral arterial disease, knee pain).


RESULTS
Being PiB+ and higher DVR in motor-related regions were associated with greater gait speed variability, cadence variability, and gait cycle time variability but not with mean gait characteristics. Associations remained similar after adjustment for gait speed and covariates, except for memory, which attenuated associations of PiB+/- with cadence variability and gait cycle time variability. Associations were prominent in men but were not found in women.


CONCLUSIONS
In usual aging, integrated temporal gait variability measures, but not mean performance, appear related to amyloid burden from cortical and motor-related cortical and subcortical regions, especially in men. Increased gait variability may be a subclinical indicator of increased amyloid burden in men.
['Tian|Qu|Q|', 'Bair|Woei-Nan|WN|', 'Resnick|Susan M|SM|', 'Bilgel|Murat|M|', 'Wong|Dean F|DF|', 'Studenski|Stephanie A|SA|']
D000368:Aged D000369:Aged, 80 and over D000375:Aging D016229:Amyloid beta-Peptides D002540:Cerebral Cortex D003430:Cross-Sectional Studies D005260:Female D005500:Follow-Up Studies D005684:Gait D006801:Humans D008297:Male D049268:Positron-Emission Tomography
Gait variability Usual aging Gait characteristics Beta-amyloid