title: Ecology of the aging human brain.
abstract: BACKGROUND
  Alzheimer disease, cerebral vascular brain injury, and isocortical Lewy body disease (LBD) are the major contributors to dementia in community- and population-based studies.
  
  
  OBJECTIVE
  To estimate the prevalence of clinically silent forms of these diseases in cognitively normal (CN) adults.
  
  
  METHODS
  Autopsy study.
  
  
  METHODS
  Community- and population based.
  
  
  METHODS
  A total of 1672 brain autopsies from the Adult Changes in Thought study, Honolulu-Asia Aging Study, Nun Study, and Oregon Brain Aging Study, of which 424 met the criteria for CN.
  
  
  METHODS
  Of these, 336 cases had a comprehensive neuropathologic examination of neuritic plaque density, Braak stage for neurofibrillary tangles, LB distribution, and number of cerebral microinfarcts.
  
  
  RESULTS
  Forty-seven percent of CN cases had moderate or frequent neuritic plaque density; of these, 6% also had Braak stage V or VI for neurofibrillary tangles. Fifteen percent of CN cases had medullary LBD; 8% also had nigral and 4% isocortical LBD. The presence of any cerebral microinfarcts was identified in 33% and of high-level cerebral microinfarcts in 10% of CN individuals. Overall, the burden of lesions in each individual and their comorbidity varied widely within each study but were similar across studies.
  
  
  CONCLUSIONS
  These data show an individually varying complex convergence of subclinical diseases in the brain of older CN adults. Appreciating this ecology should help guide future biomarker and neuroimaging studies and clinical trials that focus on community- and population-based cohorts.
authors.affiliation: Department of Pathology, University of Washington, Seattle, 98104, USA.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Sonnen
authors.forename: Karen
authors.initials: K
authors.lastname: Santa Cruz
authors.forename: Laura S
authors.initials: LS
authors.lastname: Hemmy
authors.forename: Randall
authors.initials: R
authors.lastname: Woltjer
authors.forename: James B
authors.initials: JB
authors.lastname: Leverenz
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Montine
authors.forename: Clifford R
authors.initials: CR
authors.lastname: Jack
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kaye
authors.forename: Kelvin
authors.initials: K
authors.lastname: Lim
authors.forename: Eric B
authors.initials: EB
authors.lastname: Larson
authors.forename: Lon
authors.initials: L
authors.lastname: White
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Montine
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D000544:Alzheimer Disease / Q000453:epidemiology / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D015331:Cohort Studies; D015140:Dementia, Vascular / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006254:Hawaii / Q000453:epidemiology; D006801:Humans; D020961:Lewy Body Disease / Q000453:epidemiology / Q000473:pathology*; D008297:Male; D009922:Oregon / Q000453:epidemiology; D015995:Prevalence