title: Prevalence of four subtypes of mild cognitive impairment and APOE in a Japanese community.
abstract: BACKGROUND
  The results of previous reports estimating the prevalence of mild cognitive impairment (MCI) have varied widely according to the criteria used to define MCI.
  
  
  METHODS
  We assessed the cognitive function of Japanese community-dwelling individuals >or=65 years old and attempted to estimate the prevalence of four MCI subtypes (amnestic single, amnestic multiple, nonamnestic single, and nonamnestic multiple) using two cutoffs (1 and 1.5 SD) below normative standard. Presence of apolipoprotein E4 allele (APOE4), which is known as a strong risk factor for AD, is reportedly associated with high risk of conversion from MCI to AD. We therefore calculated the frequency of APOE4 carriers for each MCI subtype.
  
  
  RESULTS
  Initially 1888 (70%) of 2698 baseline samples participated, and 1433 (53%) subjects who had complete clinical data including APOE typing remained for the final analysis. The prevalence of MCI subtypes varied within the range of 1.7-16.6%, depending on the criteria applied. Prevalence of MCI was higher using a cutoff at -1.0 SD than at -1.5 SD, and prevalence of amnestic MCI single at -1.5 SD was lowest among all subtypes of MCI. Frequency of APOE4 was higher for amnestic MCI than for non-amnestic MCI or the cognitively normal group.
  
  
  CONCLUSIONS
  The prevalence of MCI was highly dependent on the diagnostic criteria applied. A higher frequency of APOE4 in participants with amnestic MCI subtype suggested a greater risk of future AD. For future interventions to delay the onset of dementia, targeting individuals with amnestic MCI multiple at -1 SD might be desirable.
authors.affiliation: Department of Neuropsychiatry, University of Tsukuba, Tsukuba City, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Sasaki
authors.forename: Chiine
authors.initials: C
authors.lastname: Kodama
authors.forename: Shin
authors.initials: S
authors.lastname: Hidaka
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamashita
authors.forename: Toru
authors.initials: T
authors.lastname: Kinoshita
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Nemoto
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ikejima
authors.forename: Takashi
authors.initials: T
authors.lastname: Asada
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000235:genetics; D000647:Amnesia / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D053327:Apolipoprotein E4 / Q000235:genetics*; D044466:Asian People / Q000235:genetics; D003072:Cognition Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D009483:Neuropsychological Tests; D015995:Prevalence; D012307:Risk Factors
chemical_list: D053327:Apolipoprotein E4