title: A systematic review of MRI studies examining the relationship between physical fitness and activity and the white matter of the ageing brain.
abstract: Higher levels of physical fitness or activity (PFA) have been shown to have beneficial effects on cognitive function and grey matter volumes in older adults. However, the relationship between PFA and the brain's white matter (WM) is not yet well established. Here, we aim to provide a comprehensive and systematic review of magnetic resonance imaging studies examining the effects of PFA on the WM of the ageing brain. Twenty-nine studies were included in the review: eleven examined WM volume, fourteen WM lesions, and nine WM microstructure. While many studies found that higher levels of PFA were associated with greater WM volumes, reduced volume or severity of WM lesions, or improved measures of WM microstructure, a number of negative findings have also been published. Meta-analyses of global measures of WM volume and WM lesion volume yielded significant, but small, effect sizes. Overall, we found evidence for cautious support of links between PFA and WM structure, and highlighted key areas for future research including the extent to which the relationship between PFA and WM structure is anatomically specific, the influence of possible confounding factors, and the relationship between PFA, WM and cognition.
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, OX3 9DU, UK. Electronic address: claire.sexton@ndcn.ox.ac.uk.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Sexton
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, OX3 9DU, UK.
authors.forename: Jill F
authors.initials: JF
authors.lastname: Betts
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, OX3 9DU, UK.
authors.forename: Naiara
authors.initials: N
authors.lastname: Demnitz
authors.affiliation: Faculty of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Dawes
authors.affiliation: Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK.
authors.forename: Klaus P
authors.initials: KP
authors.lastname: Ebmeier
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, OX3 9DU, UK.
authors.forename: Heidi
authors.initials: H
authors.lastname: Johansen-Berg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology; D056324:Diffusion Tensor Imaging / Q000379:methods*; D019317:Evidence-Based Medicine; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066127:White Matter / Q000033:anatomy & histology* / Q000502:physiology*
keywords: Ageing; Fitness; Magnetic resonance imaging; Physical activity; Review; White matter