title: Age-related decline in task switching is linked to both global and tract-specific changes in white matter microstructure.
abstract: Task-switching performance relies on a broadly distributed frontoparietal network and declines in older adults. In this study, they investigated whether this age-related decline in task switching performance was mediated by variability in global or regional white matter microstructural health. Seventy cognitively intact adults (43-87 years) completed a cued-trials task switching paradigm. Microstructural white matter measures were derived using diffusion tensor imaging (DTI) analyses on the diffusion-weighted imaging (DWI) sequence. Task switching performance decreased with increasing age and radial diffusivity (RaD), a measure of white matter microstructure that is sensitive to myelin structure. RaD mediated the relationship between age and task switching performance. However, the relationship between RaD and task switching performance remained significant when controlling for age and was stronger in the presence of cardiovascular risk factors. Variability in error and RT mixing cost were associated with RaD in global white matter and in frontoparietal white matter tracts, respectively. These findings suggest that age-related increase in mixing cost may result from both global and tract-specific disruption of cerebral white matter linked to the increased incidence of cardiovascular risks in older adults. Hum Brain Mapp 38:1588-1603, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Functional Neuroimaging Laboratory, School of Psychology, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.
authors.forename: Todd A D
authors.initials: TA
authors.lastname: Jolly
authors.affiliation: Functional Neuroimaging Laboratory, School of Psychology, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Cooper
authors.affiliation: Functional Neuroimaging Laboratory, School of Psychology, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.
authors.forename: Jaime L
authors.initials: JL
authors.lastname: Rennie
authors.affiliation: Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.|School of Medicine and Public Health, University of Newcastle, Newcastle, Australia.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Levi
authors.affiliation: Neuroscience Research Australia, University of New South Wales, Sydney, Australia.
authors.forename: Rhoshel
authors.initials: R
authors.lastname: Lenroot
authors.affiliation: Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.|School of Medicine and Public Health, University of Newcastle, Newcastle, Australia.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Parsons
authors.affiliation: Functional Neuroimaging Laboratory, School of Psychology, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Brain and Mental Health Research, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.
authors.forename: Patricia T
authors.initials: PT
authors.lastname: Michie
authors.affiliation: Functional Neuroimaging Laboratory, School of Psychology, University of Newcastle, Newcastle, Australia.|Priority Research Centre for Stroke and Brain Injury, University of Newcastle, Newcastle, Australia.|Hunter Medical Research Institute, Newcastle, Australia.
authors.forename: Frini
authors.initials: F
authors.lastname: Karayanidis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000000981:diagnostic imaging* / Q000473:pathology*; D002318:Cardiovascular Diseases / Q000473:pathology; D003463:Cues; D056324:Diffusion Tensor Imaging; D056344:Executive Function; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D012044:Regression Analysis; D012307:Risk Factors; D066127:White Matter / Q000000981:diagnostic imaging*
keywords: aging; cognitive control; executive function; frontoparietal; mixing cost; radial diffusivity; task switching; tractography; white matter