title: Prevalence of dementia and dementing diseases in the old-old population in Japan: the Kurihara Project. Implications for Long-Term Care Insurance data.
abstract: BACKGROUND
  There have been no reports on the prevalence of dementia among the old-old people in Japan.
  
  
  METHODS
  We studied the old-old population in Kurihara, northern Japan. Analysis 1 of Participants 1 (n=590) was performed to evaluate the prevalence of dementia and dementing diseases by intensive evaluation including MRI. Analysis 2 aimed to determine a good indicator for detecting 'suspected dementia condition' based on the Long-Term Care Insurance index. Analysis 3 of Participants 2 (n=3915) aimed to estimate the prevalence of 'suspected dementia condition'.
  
  
  RESULTS
  In Analysis 1, 73 people (12.4%) were diagnosed with dementia. The most common cause was Alzheimer's disease with cerebrovascular disease. In Analysis 2, level I of the Impairment Level of Dementia was found to be a good indicator of 'suspected dementia condition'. In Analysis 3, the overall estimated prevalence of 'suspected dementia condition' was 23.6%. In men, the ratio increased gradually from 75 to 87 years old to about 20%, increased to 40% at the age of 88 and became stable thereafter. In contrast, in women, the ratio increased from 75 to 95+ years old, reaching about 70%.
  
  
  CONCLUSIONS
  The prevalence was higher than that reported previously. There was a difference between the sexes: an 'age-related' increase occurred in men and an 'ageing-related' increase in women. Alzheimer's disease with cerebrovascular disease was the most common cause, which coincided with the previous findings of individuals aged 65 years and older; however, the ratio of mixed dementia was greater.
authors.affiliation: Department of Geriatric Behavioral Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan. k-meg@umin.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Meguro
authors.forename: Naofumi
authors.initials: N
authors.lastname: Tanaka
authors.forename: Mari
authors.initials: M
authors.lastname: Kasai
authors.forename: Kei
authors.initials: K
authors.lastname: Nakamura
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakatsuka
authors.forename: Masayuki
authors.initials: M
authors.lastname: Satoh
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ouchi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007353:Insurance, Long-Term Care / Q000706:statistics & numerical data*; D007564:Japan / Q000453:epidemiology; D008279:Magnetic Resonance Imaging; D008297:Male; D010865:Pilot Projects; D015995:Prevalence; D015397:Program Evaluation; D017678:Sex Distribution; D012737:Sex Factors