title: Coupled changes in brain white matter microstructure and fluid intelligence in later life.
abstract: Understanding aging-related cognitive decline is of growing importance in aging societies, but relatively little is known about its neural substrates. Measures of white matter microstructure are known to correlate cross-sectionally with cognitive ability measures, but only a few small studies have tested for longitudinal relations among these variables. We tested whether there were coupled changes in brain white matter microstructure indexed by fractional anisotropy (FA) and three broad cognitive domains (fluid intelligence, processing speed, and memory) in a large cohort of human participants with longitudinal diffusion tensor MRI and detailed cognitive data taken at ages 73 years (n = 731) and 76 years (n = 488). Longitudinal changes in white matter microstructure were coupled with changes in fluid intelligence, but not with processing speed or memory. Individuals with higher baseline white matter FA showed less subsequent decline in processing speed. Our results provide evidence for a longitudinal link between changes in white matter microstructure and aging-related cognitive decline during the eighth decade of life. They are consistent with theoretical perspectives positing that a corticocortical "disconnection" partly explains cognitive aging.
authors.affiliation: Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and stuart.ritchie@ed.ac.uk.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Ritchie
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SA, UK, Brain Research Imaging Centre, The University of Edinburgh, Edinburgh EH4 2XU, UK, Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE), Edinburgh, UK.
authors.forename: Mark E
authors.identifier: http://orcid.org/0000-0002-0490-0845
authors.initials: ME
authors.lastname: Bastin
authors.affiliation: Department of Psychology, University of Texas, Austin, Texas 78712-0187, and.
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Tucker-Drob
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SA, UK, Brain Research Imaging Centre, The University of Edinburgh, Edinburgh EH4 2XU, UK, Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE), Edinburgh, UK.
authors.forename: Susana Muñoz
authors.initials: SM
authors.lastname: Maniega
authors.affiliation: Department of Psychology, University of Texas, Austin, Texas 78712-0187, and.
authors.forename: Laura E
authors.identifier: http://orcid.org/0000-0001-7254-5702
authors.initials: LE
authors.lastname: Engelhardt
authors.affiliation: Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Cox
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SA, UK, Brain Research Imaging Centre, The University of Edinburgh, Edinburgh EH4 2XU, UK, Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE), Edinburgh, UK.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Royle
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Department of Psychology, Heriot-Watt University, Edinburgh EH14 4AS, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Gow
authors.affiliation: Department of Psychology.
authors.forename: Janie
authors.initials: J
authors.lastname: Corley
authors.affiliation: Department of Psychology.
authors.forename: Alison
authors.initials: A
authors.lastname: Pattie
authors.affiliation: Department of Psychology.
authors.forename: Adele M
authors.identifier: http://orcid.org/0000-0003-4541-4568
authors.initials: AM
authors.lastname: Taylor
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SA, UK, Brain Research Imaging Centre, The University of Edinburgh, Edinburgh EH4 2XU, UK, Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE), Edinburgh, UK.
authors.forename: Maria Del C
authors.initials: Mdel C
authors.lastname: Valdés Hernández
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Alzheimer Scotland Dementia Research Centre, The University of Edinburgh, Edinburgh EH8 9JZ, UK.
authors.forename: John M
authors.initials: JM
authors.lastname: Starr
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, and Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SA, UK, Brain Research Imaging Centre, The University of Edinburgh, Edinburgh EH4 2XU, UK, Scottish Imaging Network, a Platform for Scientific Excellence (SINAPSE), Edinburgh, UK.
authors.forename: Joanna M
authors.identifier: http://orcid.org/0000-0002-9812-6642
authors.initials: JM
authors.lastname: Wardlaw
authors.affiliation: Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
mesh_terms: D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D015331:Cohort Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D012189:Retrospective Studies; D013223:Statistics as Topic; D066127:White Matter / Q000033:anatomy & histology*
keywords: cognitive aging; diffusion tensor imaging; fluid intelligence; fractional anisotropy; processing speed; white matter microstructure