[p1–117]: Influence of Brain Amyloid Positivity on Cognitive Dual‐task Load‐induced Gait Slowing in Cognitively Normal, Mobility Unimpaired Older Adults
Year: 2017
Type: article
Study design: Observational Study
Abstract: Slowing of gait speed while walking and performing cognitive tasks (dual-tasking) is related to brain amyloid burden in cognitively and mobility unimpaired (CMU) older adults. Working-memory and motor-sequencing decline early in Alzheimer's disease (AD), and may influence dual-task gait relative to the cognitive task load; amyloid burden may further influence this relationship in CMU elders at-risk for AD. We assessed the influence of amyloid positivity on gait speed change induced by working-memory and motor-sequencing dual-tasking of increasing complexity in CMU elders. Community-dwelling elders were carefully screened for cognitive and mobility impairment. Brain amyloid burden was determined using the Pittsburgh B (PiB) ligand on PET imaging. Global cortical amyloid deposition was dichotomized as high-amyloid (PiB(+)) or low-amyloid (PiB(-)), determined by average of six cortical regional standardized uptake value ratios (cutoff=1.4) referenced to cerebellum. Verbal working-memory n-back paradigms (0-back, 1-back, and 2-back), and motor-sequencing on the dominant hand (simple sequencing: open-close-open, and complex sequencing: fist-palm-side-fist) was assessed while standing, and while walking. Gait speed was measured on the GaitMat II on usual walking, and while performing the 3 working memory and 2 motor sequencing tasks. Linear mixed models were used for statistical analysis. PiB(+) (n=16) and PiB(-) (n=11), mean age=75 years, were similar in demographics, general cognitive and physical performance measures, and usual gait speed (1.14 vs 1.17 m/sec, p=0.8). PiB(+) subjects reduced gait speed on all working-memory tasks by 0.22 (0-back), 0.22 (1-back) and 0.26 (2-back) m/sec (all p <0.0001), and on both motor-sequencing tasks by 0.11 (simple, p=0.005) and 0.37 (complex, p=<0.0001) m/sec; PiB(-) subjects reduced gait speed by 0.04 (p=0.5), 0.16 (p=0.004) and 0.13 (p=0.007) m/sec on the respective working-memory tasks (Figure-1), and by none (p=0.8) and 0.22 m/sec (p<0.0001) on the respective motor-sequencing tasks (Figure-2). Dual-task induced gait speed declines were greater in the PiB(+) than in PiB(-) individuals by 0.18 (p=0.004), 0.07 (p=0.3) and 0.13 (p=0.03) m/sec on the respective working-memory (Figure-1), and 0.12 (p=0.08) and 0.15 (p=0.02) m/sec on the respective motor-sequencing tasks (Figure-2). Amyloid positivity in CMU older adults may influence gait slowing induced by increasing complexity of working-memory and motor-sequencing dual-task conditions. Working-memory dual-tasks of increasing complexity. Significant dual-task gait speed declines from usual walk within groups (‡ = p<0.001 and †= p<0.01), and dual-task gait speed differences between groups (**= p<0.01, *= p<0.05) are shown. Motor-sequencing dual-tasks of increasing complexity. Significant dual-task gait speed declines from usual walk within groups (‡ = p<0.001 and † = p<0.01), and dual-task gait speed differences between groups (**= p<0.01, *= p<0.05) are shown.
Source: Alzheimer s & Dementia
Authors: Neelesh K. Nadkarni, Subashan Perera, Beth E. Snitz, Oscar L. Lopez, Bill E. Klunk
Institution: University of Pittsburgh
Language: English
Field: Health Professions
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2765623133