Grant: Travel Awards - Institute Community Support

Background: Impaired mobility in older adults contribute to late-life disability and is associated cognitive and neurological impairments. Evidence suggests that cerebral small vessel ischemic disease negatively impacts mobility. Specifically, white matter lesions are associated with slow gait speed and falls. In addition, motor slowing appears to precede and may predict the onset of mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, there is limited research investigating the specific role of AD pathology in the evolution of impaired mobility. The objective of this study was to examine the association between cerebral beta-amyloid deposition and mobility performance in older adults with MCI or dementia. Methods: Thirty-one participants with MCI or dementia completed an 11C Pittsburgh compound B (PIB) position emission tomography (PET) scan to quantify global amyloid deposition. Magnetic resonance or computerized tomography images were used to rate white matter lesion load using the Fazekas scale. Mobility was assessed using the Timed Up and Go Test and usual gait speed. The TUGT measures the time it takes to stand up from an armchair, walk 3m, turn, walk back to the chair, and sit down. Usual gait speed was measured over 4m. Multiple linear regression analyses examined the relationship between amyloid deposition and mobility performance (i.e., TUGT and gait speed), adjusting for age, Fazekas score, and body mass index. Results: Higher levels of cerebral amyloid was significantly associated with slower gait speed and longer time to complete the TUGT after accounting for the effect of age, body mass index, and Fazekas score. Conclusion: Cerebral beta-amyloid deposition is associated with impaired mobility in older adults with MCI or dementia, independent of white matter lesion load.