title: Dementia-free centenarians.
abstract: BACKGROUND
  A small percentage of centenarians, about 15-25%, are functionally cognitively intact. Among those who are not cognitively intact at 100, approximately 90% delayed the onset of clinically evident impairment at least until the average age of 92 yr.
  
  
  OBJECTIVE
  To review current and past findings related to the prevalence and incidence of dementia amongst the exceptionally long-lived.
  
  
  METHODS
  Findings from the various centenarian studies, world-wide, are reviewed.
  
  
  RESULTS
  Neuropsychological and neuropathological correlations thus far suggest that there are centenarians who demonstrate no evidence of neurodegenerative disease. There also appear to be centenarians who despite the substantial presence of neuropathological markers of Alzheimer's disease did not meet clinical criteria for having dementia, thus suggesting the existence of cognitive reserve. Epigenic studies suggest a significant familial component to these survival advantages.
  
  
  CONCLUSIONS
  Centenarians are of scientific interest as a human model of relative resistance to dementia.
authors.affiliation: Geriatrics Section, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA 02118, USA. thperls@bu.edu
authors.forename: Thomas
authors.initials: T
authors.lastname: Perls
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004777:Environment; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D007113:Immunity, Innate; D008136:Longevity / Q000235:genetics*; D008297:Male; D019636:Neurodegenerative Diseases / Q000209:etiology / Q000235:genetics; D009483:Neuropsychological Tests