title: Impact of Depressive Symptoms on Conversion from Mild Cognitive Impairment Subtypes to Alzheimer's Disease: A Community-Based Longitudinal Study.
abstract: BACKGROUND
  While longitudinal studies have investigated the relationships between mild cognitive impairment (MCI) subtypes and dementia subtypes, the results have been contradictory. In addition, some research shows that depression accompanied by MCI might increase the risk of Alzheimer's disease (AD).
  
  
  OBJECTIVE
  The aim of this study is to longitudinally investigate the relationships between MCI subtypes and dementia subtypes, with special attention to the effect of comorbid depressive symptoms in a Japanese rural community.
  
  
  METHODS
  Non-demented participants (n = 802) completed a baseline and follow-up study. Outcomes were conversion to dementia especially AD, MCI, or no conversion. A complementary log-log analysis was conducted to investigate the risk of dementia and AD in amnestic MCI (aMCI) compared to nonamnestic MCI (naMCI) groups. The impact of depressive symptoms on the transition from MCI to AD and from cognitively normal to MCI or AD was also analyzed.
  
  
  RESULTS
  The risk of developing dementia, in particular AD, for the aMCI group was significantly higher than that for the naMCI group. In the aMCI group, the presence of depressive symptoms increased the risk of developing AD, but depressive symptoms in the naMCI group did not. In the cognitively normal group, the presence of depressive symptoms increased the risk of aMCI but not naMCI or AD.
  
  
  CONCLUSIONS
  MCI subtyping could be useful in finding a prodrome for dementia and in particular for AD. The differing impacts of depressive symptoms on the development of AD suggest that the relationship between depressive symptoms and cognitive impairment could differ in aMCI and naMCI patients.
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.|Department of Psychiatry, Tokyo Adachi Hospital, Tokyo, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Kida
authors.affiliation: Department of Neuropsychiatry, University of Tsukuba, Ibaraki, Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Nemoto
authors.affiliation: Yashio Central General Hospital, Saitama, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ikejima
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Shogyoku
authors.initials: S
authors.lastname: Bun
authors.affiliation: Biostatistics Center, Kurume University, Fukuoka, Japan.
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Kakuma
authors.affiliation: Department of Neuropsychiatry, University of Tsukuba, Ibaraki, Japan.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Mizukami
authors.affiliation: Department of Neuropsychiatry, University of Tsukuba, Ibaraki, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Asada
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology*; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology*; D003863:Depression / Q000175:diagnosis* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D062706:Prodromal Symptoms; D011379:Prognosis; D012306:Risk
keywords: Alzheimer’s disease; community; conversion; depressive symptoms; mild cognitive impairment