title: Effects of Tooth Loss and the Apolipoprotein E ɛ4 Allele on Mild Memory Impairment in the Fujiwara-kyo Study of Japan: A Nested Case-Control Study.
abstract: Several studies have suggested that periodontal disease can exacerbate the pro-inflammatory status of the brain. Tooth loss is one of the alternative evaluation indices of periodontal disease. There are few data on the relationship between tooth loss and memory impairment, depending on the apolipoprotein E (APOE) ɛ4 genotype.
  
  
  
  To determine if tooth loss is associated with mild memory impairment (MMI) and if this association is modified by the presence of the APOEɛ4 allele.
  
  
  
  A nested case-control study was conducted from 2007 to 2012 in Japan. Five hundred and thirty-seven Japanese subjects aged 65 years and over who were cognitively intact at baseline were analyzed. MMI at follow-up was evaluated.
  
  
  
  The median number of teeth at baseline was significantly lower in MMI participants (n = 179) than in controls (n = 358) (MMI: median 21.0, interquartile range 10.0-25.0 versus controls: 24.0, 14.0-27.0). After adjustment for demographics, vascular risk factors, and APOEɛ4 allele, the multivariate adjusted odds ratio (OR) of ≤8 teeth was 1.97 (95% confidence interval [CI], 1.13-3.44) compared to 25-32 teeth. Participants with both the presence of at least 1 APOEɛ4 allele and ≤8 teeth had a higher risk of MMI compared with those with neither (OR, 2.82; 95% CI, 1.15-6.91). Those with either risk factor alone did not have a higher risk of MMI.
  
  
  
  A lower number of teeth is related to risk of MMI. This may be primarily true for those individuals with an APOEɛ4 allele.
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University, Nara, Japan.
authors.forename: Nozomi
authors.initials: N
authors.lastname: Okamoto
authors.affiliation: Mie Prefectural Mental Medical Center, Mie, Japan.|Department of Psychiatry, Nara Medical University, Nara, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Morikawa
authors.affiliation: Konan Women's University, Hyogo, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Amano
authors.affiliation: Department of Food and Nutrition, Tezukayama University, Nara, Japan.
authors.forename: Motokazu
authors.initials: M
authors.lastname: Yanagi
authors.affiliation: Department of Biochemistry, Nara Medical University, Nara, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Takasawa
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University, Nara, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Kurumatani
mesh_terms: D000368:Aged; D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008569:Memory Disorders / Q000150:complications* / Q000453:epidemiology / Q000235:genetics*; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D016388:Tooth Loss / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics
chemical_list: D001057:Apolipoproteins E
keywords: APOE ɛ4 allele; community-based; memory decline; nested case-control study; tooth loss