title: Associations of neighborhood environment with brain imaging outcomes in the Australian Imaging, Biomarkers and Lifestyle cohort.
abstract: BACKGROUND
  "Walkable" neighborhoods offer older adults opportunities for activities that may benefit cognition-related biological mechanisms. These have not previously been examined in this context.
  
  
  METHODS
  We objectively assessed neighborhood walkability for participants (n = 146) from the Australian Imaging, Biomarkers and Lifestyle study with apolipoprotein E (APOE) genotype and two 18-month-apart brain volumetric and/or amyloid β burden assessments. Linear mixed models estimated associations of neighborhood walkability with levels and changes in brain imaging outcomes, the moderating effect of APOE ε4 status, and the extent to which associations were explained by physical activity.
  
  
  RESULTS
  Cross-sectionally, neighborhood walkability was predictive of better neuroimaging outcomes except for left hippocampal volume. These associations were to a small extent explained by physical activity. APOE ε4 carriers showed slower worsening of outcomes if living in walkable neighborhoods.
  
  
  CONCLUSIONS
  These findings indicate associations between neighborhood walkability and brain imaging measures (especially in APOE ε4 carriers) minimally attributable to physical activity.
authors.affiliation: Institute for Health and Ageing, Australian Catholic University, Melbourne, Victoria, Australia; School of Public Health, The University of Hong Kong, Hong Kong, China; School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia. Electronic address: ecerin@hku.hk.
authors.forename: Ester
authors.initials: E
authors.lastname: Cerin
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Perth, Western Australia, Australia.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Rainey-Smith
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; National Ageing Research Institute, Parkville, Victoria, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Nicola T
authors.initials: NT
authors.lastname: Lautenschlager
authors.affiliation: CSIRO Food and Nutrition, Parkville, Victoria, Australia.
authors.forename: S Lance
authors.initials: SL
authors.lastname: Macaulay
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Fowler
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Robertson
authors.affiliation: Austin Health, Heidelberg, Victoria, Australia.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia; Cogstate Ltd., Melbourne, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Maruff
authors.affiliation: Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital), Perth, Western Australia, Australia; Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Perth, Western Australia, Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Colin L
authors.initials: CL
authors.lastname: Masters
authors.affiliation: Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Ellis
mesh_terms: D000368:Aged; D001057:Apolipoproteins E / Q000235:genetics; D001315:Australia; D015415:Biomarkers; D001921:Brain / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004777:Environment; D005260:Female; D006579:Heterozygote; D006801:Humans; D008019:Life Style; D008279:Magnetic Resonance Imaging; D008297:Male; D059906:Neuroimaging; D009929:Organ Size; D049268:Positron-Emission Tomography; D012111:Residence Characteristics; D012959:Socioeconomic Factors; D016138:Walking
chemical_list: D001057:Apolipoproteins E; D015415:Biomarkers
keywords: Amyloid beta depositions; Apolipoprotein E genotype; Brain volumetric measures; Community dwellers; Enriched environment; Hippocampus; Place of residence; Walkability