title: Brain volume decline in aging: evidence for a relation between socioeconomic status, preclinical Alzheimer disease, and reserve.
abstract: OBJECTIVE
  To assess the relation between socioeconomic status (SES) and structural brain change in nondemented older adults and to ascertain the potential role of preclinical Alzheimer disease (AD).
  
  
  METHODS
  Cross-sectional and longitudinal observation.
  
  
  METHODS
  Alzheimer's Disease Research Center, St Louis, Missouri.
  
  
  METHODS
  Volunteer sample of 362 nondemented adults aged 18 to 93 years. The main cohort of 100 was evaluated for dementia and SES; a Clinical Dementia Rating (CDR) of 0 (no dementia) and middle, high-middle, or high SES was required for eligibility. All 362 received magnetic resonance imaging; of the main 100, 91 received follow-up clinical assessment, and 33 received follow-up magnetic resonance imaging over at least a 3-year interval. A separate sample of 58 CDR 0 participants (aged 47 to 86 years) took part in amyloid imaging with Pittsburgh Compound B (PiB) labeled with radioactive carbon ((11)C).
  
  
  METHODS
  Whole-brain volume adjusted for head size (aWBV) and change per year.
  
  
  RESULTS
  aWBV declined by 0.22% per year between the ages of 20 and 80 years with accelerated decline in advanced aging. Controlling for effects of age and sex in older adults (>65 years) with CDR 0, higher SES was associated with smaller aWBV (3.8% difference spanning the sample range from middle to high privilege, P< .01) and more rapid volume loss (0.39% per year to 0.68% per year from middle to high privilege, P< .05). aWBV was reduced by 2.5% in individuals positive for PiB binding (n=9) as compared with individuals negative for PiB binding (n=49, P< .05), supporting an influence of undetected preclinical AD. Follow-up clinical data revealed that brain volume reduction associated with SES was greater in those who later developed very mild dementia (preclinical CDR 0 group, n=19) compared with those who remained nondemented (stable CDR 0 group, n=64; group x SES interaction, P< .05).
  
  
  CONCLUSIONS
  Privileged nondemented older adults harbor more preclinical brain atrophy, consistent with their having greater reserve against the expression of AD.
authors.affiliation: Division of Biology and Biomedical Sciences, Washington University Medical School, St Louis, Missouri, USA. anthony.fotenos@wustl.edu
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Fotenos
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mintun
authors.forename: Abraham Z
authors.initials: AZ
authors.lastname: Snyder
authors.forename: John C
authors.initials: JC
authors.lastname: Morris
authors.forename: Randy L
authors.initials: RL
authors.lastname: Buckner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000523:psychology; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000473:pathology* / Q000523:psychology; D001921:Brain / Q000033:anatomy & histology* / Q000254:growth & development* / Q000473:pathology; D003071:Cognition / Q000502:physiology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003704:Dementia / Q000473:pathology / Q000523:psychology; D005260:Female; D006257:Head / Q000033:anatomy & histology; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D058225:Plaque, Amyloid / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography; D012923:Social Class