title: Prevalence of dementia and distribution of ApoE alleles in Japanese centenarians: an almost-complete survey in Yamanashi Prefecture, Japan.
abstract: OBJECTIVE
  To determine the prevalence and types of dementia in centenarians and to examine whether the ApoE epsilon 4 allele has significant impact on the development of Alzheimer's disease (AD) in the population.
  
  
  METHODS
  Cross-sectional study and a 6-month prospective study.
  
  
  METHODS
  Yamanashi Prefecture, Japan.
  
  
  METHODS
  Forty-seven centenarians participated in the study to determine the prevalence and types of dementia. Thirty-three of the 47 participated in the study of ApoE genotyping. As controls, 224 demented older adults participated in the genetic study. Their age at onset was < 90 years.
  
  
  RESULTS
  Prevalence of dementia based on DSM-III-R; types of dementia based on NINCDS-ADRDA and ICD-10; distribution on ApoE alleles in the centenarians and in the controls; and the 6-month mortality rate of the subjects.
  
  
  RESULTS
  Of 47 centenarians, 70.2% had dementia, and AD accounted for the majority (75.8%) of the dementia cases. The distribution of ApoE alleles in all the subjects and the AD subjects was epsilon 2: 4.6% vs. 0%; epsilon 3: 90.1% vs. 94.1%; epsilon 4: 4.6% vs. 5.9%. The frequency of the epsilon 4 allele in the AD patients showed a tendency to decrease with increasing age, ranging from 38% for those with an age at onset of < 60 years to 22% for those with an age at onset of ranging from 80 to 89 years. The 6-month mortality rate was 27% (9/33) for the demented centenarians, whereas none of the 14 nondemented centenarians died.
  
  
  CONCLUSIONS
  This almost-complete survey, conducted in a prefecture of Japan, revealed a high prevalence of dementia in centenarians. The ApoE epsilon 4 allele does not have an impact on the development of AD in centenarians.
authors.affiliation: Department of Neurology and Psychiatry, Yamanashi Medical University, Tamaho, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Asada
authors.forename: Z
authors.initials: Z
authors.lastname: Yamagata
authors.forename: T
authors.initials: T
authors.lastname: Kinoshita
authors.forename: A
authors.initials: A
authors.lastname: Kinoshita
authors.forename: T
authors.initials: T
authors.lastname: Kariya
authors.forename: A
authors.initials: A
authors.lastname: Asaka
authors.forename: T
authors.initials: T
authors.lastname: Kakuma
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003704:Dementia / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D015577:Geriatric Assessment; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D011446:Prospective Studies
chemical_list: D053327:Apolipoprotein E4; D001057:Apolipoproteins E