title: Sleep quality and preclinical Alzheimer disease.
abstract: OBJECTIVE
  Sleep and circadian problems are very common in Alzheimer disease (AD). Recent animal studies suggest a bidirectional relationship between sleep and β-amyloid (Aβ), a key molecule involved in AD pathogenesis.
  
  
  OBJECTIVE
  To test whether Aβ deposition in preclinical AD, prior to the appearance of cognitive impairment, is associated with changes in quality or quantity of sleep.
  
  
  METHODS
  Cross-sectional study conducted from October 2010 to June 2012.
  
  
  METHODS
  General community volunteers at the Washington University Knight Alzheimer's Disease Research Center.
  
  
  METHODS
  Cognitively normal individuals (n = 145) 45 years and older were recruited from longitudinal studies of memory and aging at the Washington University Knight Alzheimer's Disease Research Center. Valid actigraphy data were recorded in 142. The majority (124 of 142) were recruited from the Adult Children Study, in which all were aged 45 to 75 years at baseline and 50% have a parental history of late-onset AD. The rest were recruited from a community volunteer cohort in which all were older than 60 years and healthy at baseline.
  
  
  METHODS
  Sleep was objectively measured using actigraphy for 2 weeks. Sleep efficiency, which is the percentage of time in bed spent asleep, was the primary measure of sleep quality. Total sleep time was the primary measure of sleep quantity. Cerebrospinal fluid Aβ42 levels were used to determine whether amyloid deposition was present or absent. Concurrent sleep diaries provided nap information.
  
  
  RESULTS
  Amyloid deposition, as assessed by Aβ42 levels, was present in 32 participants (22.5%). This group had worse sleep quality, as measured by sleep efficiency (80.4% vs 83.7%), compared with those without amyloid deposition, after correction for age, sex, and APOEε4 allele carrier status (P = .04). In contrast, quantity of sleep was not significantly different between groups, as measured by total sleep time. Frequent napping, 3 or more days per week, was associated with amyloid deposition (31.2% vs 14.7%; P = .03).
  
  
  CONCLUSIONS
  Amyloid deposition in the preclinical stage of AD appears to be associated with worse sleep quality but not with changes in sleep quantity.
authors.affiliation: Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Yo-El S
authors.initials: YE
authors.lastname: Ju
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: McLeland
authors.forename: Cristina D
authors.initials: CD
authors.lastname: Toedebusch
authors.forename: Chengjie
authors.initials: C
authors.lastname: Xiong
authors.forename: Anne M
authors.initials: AM
authors.lastname: Fagan
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Duntley
authors.forename: John C
authors.initials: JC
authors.lastname: Morris
authors.forename: David M
authors.initials: DM
authors.lastname: Holtzman
mesh_terms: D056044:Actigraphy; D000368:Aged; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000150:complications / Q000503:physiopathology*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid; D062706:Prodromal Symptoms; D012893:Sleep Wake Disorders / Q000134:cerebrospinal fluid / Q000209:etiology / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)