title: Community environment, cognitive impairment and dementia in later life: results from the Cognitive Function and Ageing Study.
abstract: BACKGROUND
  Few studies have investigated the impact of the community environment, as distinct from area deprivation, on cognition in later life. This study explores cross-sectional associations between cognitive impairment and dementia and environmental features at the community level in older people.
  
  
  METHODS
  The postcodes of the 2,424 participants in the year-10 interview of the Cognitive Function and Ageing Study in England were mapped into small area level geographical units (Lower-layer Super Output Areas) and linked to environmental data in government statistics. Multilevel logistic regression was conducted to investigate associations between cognitive impairment (defined as MMSE ≤ 25), dementia (organicity level ≥3 in GMS-AGECAT) and community level measurements including area deprivation, natural environment, land use mix and crime. Sensitivity analyses tested the impact of people moving residence within the last two years.
  
  
  RESULTS
  Higher levels of area deprivation and crime were not significantly associated with cognitive impairment and dementia after accounting for individual level factors. Living in areas with high land use mix was significantly associated with a nearly 60% reduced odds of dementia (OR: 0.4; 95% CI: 0.2, 0.8) after adjusting for individual level factors and area deprivation, but there was no linear trend for cognitive impairment. Increased odds of dementia (OR: 2.2, 95% CI: 1.2, 4.2) and cognitive impairment (OR: 1.4, 95% CI: 1.0, 2.0) were found in the highest quartile of natural environment availability. Findings were robust to exclusion of the recently relocated.
  
  
  CONCLUSIONS
  Features of land use have complex associations with cognitive impairment and dementia. Further investigations should focus on environmental influences on cognition to inform health and social policies.
authors.affiliation: Cambridge institute of Public Health, University of Cambridge, Cambridge, UK.
authors.forename: Yu-Tzu
authors.initials: YT
authors.lastname: Wu
authors.affiliation: Centre for Global Mental Health, Health Services and Population Research, Institute of Psychiatry, King's College London, London, UK.
authors.forename: A Matthew
authors.initials: AM
authors.lastname: Prina
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Jones
authors.affiliation: Cambridge institute of Public Health, University of Cambridge, Cambridge, UK.
authors.forename: Linda E
authors.initials: LE
authors.lastname: Barnes
authors.affiliation: MRC Biostatistics Unit, University of Cambridge, Cambridge, UK.
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Matthews
authors.affiliation: Cambridge institute of Public Health, University of Cambridge, Cambridge, UK.
authors.forename: Carol
authors.initials: C
authors.lastname: Brayne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology*; D003704:Dementia / Q000453:epidemiology / Q000209:etiology*; D004739:England / Q000453:epidemiology; D004777:Environment; D005260:Female; D006801:Humans; D057187:Independent Living; D016015:Logistic Models; D008297:Male; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012307:Risk Factors; D012931:Social Environment
keywords: cognitive impairment; dementia; neighbourhood/community environment; older people