Cerebral Amyloid Deposition and Dual-Tasking in Cognitively Normal, Mobility Unimpaired Older Adults

BACKGROUND: We examined relationships between cerebral amyloid-beta (Aβ) and cognitive-gait dual-task performance in 27 cognitively normal, mobility unimpaired elders. METHODS: We assessed Aβ on Pittsburgh Compound B (PiB)-PET. We measured gait speed separately and while performing working-memory, response-inhibition, motor-sequencing, and phone-dialing tasks. We compared dual-task costs on gait and cognitive performance in high-Aβ (PiB(+)) and low-Aβ (PiB(-)) groups and examined the association between Aβ and dual-task performance decrements. RESULTS: PiB(+) (n = 16) were comparable with the PiB(-) (n = 11) individuals on demographics, general cognitive and physical performance, and key brain MRI characteristics. PiB(+) group demonstrated greater dual-task costs on gait speed on all cognitive tasks (p < .05) except on response inhibition. Dual-task costs on cognition were similar between groups. Overall, Aβ was associated with dual-task decrement on gait speed but not on dual-task decrement on cognitive performance. CONCLUSIONS: Preliminary evidence indicates that cerebral Aβ is associated with gait slowing on dual-tasking in healthy older adults.