title: Associations between level and change in physical function and brain volumes.
abstract: BACKGROUND
  Higher levels of fitness or physical function are positively associated with cognitive outcomes but the potential underlying mechanisms via brain structure are still to be elucidated in detail. We examined associations between brain structure and physical function (contemporaneous and change over the previous three years) in community-dwelling older adults.
  
  
  RESULTS
  Participants from the Lothian Birth Cohort 1936 (N=694) underwent brain MRI at age 73 years to assess intracranial volume, and the volumes of total brain tissue, ventricles, grey matter, normal-appearing white matter, and white matter lesions. At ages 70 and 73, physical function was assessed by 6-meter walk, grip strength, and forced expiratory volume. A summary 'physical function factor' was derived from the individual measures using principal components analysis. Performance on each individual physical function measure declined across the three year interval (p<0.001). Higher level of physical function at ages 70 and 73 was associated with larger total brain tissue and white matter volumes, and smaller ventricular and white matter lesion volumes (standardized β ranged in magnitude from 0.07 to 0.17, p<0.001 to 0.034). Decline in physical function from age 70 to 73 was associated with smaller white matter volume (0.08, p<0.01, though not after correction for multiple testing), but not with any other brain volumetric measurements.
  
  
  CONCLUSIONS
  Physical function was related to brain volumes in community-dwelling older adults: declining physical function was associated with less white matter tissue. Further study is required to explore the detailed mechanisms through which physical function might influence brain structure, and vice versa.
authors.affiliation: Brain Research Imaging Centre, Division of Neuroimaging Sciences, School of Clinical Sciences, University of Edinburgh, Edinburgh, United Kingdom ; Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, United Kingdom ; SINAPSE (Scottish Imaging Network, A Platform for Scientific Excellence) Collaboration, Edinburgh, United Kingdom ; Department of Computer Science, Faculty of Science, Lagos State University, Lagos, Nigeria.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Aribisala
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Gow
authors.forename: Mark E
authors.initials: ME
authors.lastname: Bastin
authors.forename: Maria
authors.initials: M
authors.lastname: del Carmen Valdés Hernández
authors.forename: Catherine
authors.initials: C
authors.lastname: Murray
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Royle
authors.forename: Susana
authors.initials: S
authors.lastname: Muñoz Maniega
authors.forename: John M
authors.initials: JM
authors.lastname: Starr
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Wardlaw
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009929:Organ Size; D012307:Risk Factors