title: Impact of subcortical hyperintensities on dual-tasking in Alzheimer disease and aging.
abstract: Subcortical hyperintensities (SHs) on brain magnetic resonance imaging are associated with cognitive and gait impairment in elderly but their impact on dual-tasking (performing cognitive tasks while walking) in patients with Alzheimer disease (AD) is unknown. This study explored the costs of dual-tasking in relation to SH severity in AD and normal controls (NCs). Cadence while walking on a treadmill, and speed-accuracy-tradeoff (SAT), on 3 working memory tasks, were measured during single-task and dual-task conditions. Dual-task costs (DTC) on SAT, cadence, and overall DTC were measured for each of these tasks. On visual rating of SH severity, AD and NC groups were subdivided into high-SH and low-SH subgroups. Compared with the NC, the AD group performed poorly on all working memory tasks across both conditions, decreased cadence on dual-tasking, and showed a decrement in overall DTC (all P<0.01). When grouped according to SH severity, the low-SH-NC group performed superiorly on working memory tasks (P<0.001) and the high-SH-AD group (P=0.001) showed a decrease in dual-task costs of cadence. Although the AD group showed a decrement in overall DTC (P<0.01) compared with NC, when assessed in terms of SH severity, the high-SH-AD group showed the largest decrement in DTC (P<0.01). Greater SH severity is associated with a decrement in overall dual-tasking ability in AD.
authors.affiliation: Division of Geriatric Medicine and Gerontology, Department of Medicine, University of Pittsburgh Medical Centre, University of Pittsburgh, PA, USA. nadkarnink@upmc.edu
authors.forename: Neelesh K
authors.initials: NK
authors.lastname: Nadkarni
authors.forename: Brian
authors.initials: B
authors.lastname: Levine
authors.forename: William E
authors.initials: WE
authors.lastname: McIlroy
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Black
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000544:Alzheimer Disease / Q000473:pathology / Q000503:physiopathology*; D001921:Brain / Q000473:pathology; D003071:Cognition / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D013647:Task Performance and Analysis; D016138:Walking / Q000502:physiology*