Cross-Sectional and Prospective Associations Between β-Amyloid in the Brain and Chair Rise Performance in Nondementia Older Adults With Spontaneous Memory Complaints

Background: The objectives of this study were to examine the cross-sectional and prospective associations of muscle functional performance as assessed by a chair rise test and brain amyloid load among nondemented older adults with spontaneous memory complaints. Methods: This is a secondary analysis, with an observational design, using data from the MAPT randomized controlled trial. Individuals assessed for brain amyloid load (florbetapir F18 positron emission tomography) and without clinical dementia (N = 269 aged 75.2 +/- 4.2 years; 60.2% women) participated in the study. Cortical and regional standard uptake value ratios (SUVRs) were obtained. The main outcome measure was the 5-repetition chair rise performance (maximum speed-higher is better), which was assessed at baseline and at 6, 12, 24, and 36 months. Adjusted multiple linear (cross-sectional) and mixed-effect (overtime) regressions were performed. Results: Any of mean cortical (regions of interest) and each regional SUVRs (anterior cingulate, anterior putamen, caudate, hippocampus, medial orbitofrontal cortex, occipital cortex, parietal cortex, pons, posterior cingulate, posterior putamen, precuneus, semioval center, and temporal cortex) were not associated to chair rise after adjustment for multiplicity. These findings were obtained for both cross-sectional and prospective associations. Conclusions: Brain amyloid was not found to be associated to chair rise performance in nondemented older adults with memory complaints. Potential mechanisms on the links, if any, of amyloid load with physical performance are probably not dependent on muscle function.