title: Effects of age and amyloid deposition on Aβ dynamics in the human central nervous system.
abstract: BACKGROUND
  The amyloid hypothesis predicts that increased production or decreased clearance of β-amyloid (Aβ) leads to amyloidosis, which ultimately culminates in Alzheimer disease (AD).
  
  
  OBJECTIVE
  To investigate whether dynamic changes in Aβ levels in the human central nervous system may be altered by aging or by the pathology of AD and thus contribute to the risk of AD.
  
  
  METHODS
  Repeated-measures case-control study.
  
  
  METHODS
  Washington University School of Medicine in St Louis, Missouri.
  
  
  METHODS
  Participants with amyloid deposition, participants without amyloid deposition, and younger normal control participants.
  
  
  METHODS
  In this study, hourly cerebrospinal fluid (CSF) Aβ concentrations were compared with age, status of amyloid deposition, electroencephalography, and video recording data.
  
  
  RESULTS
  Linear increases were observed over time in the Aβ levels in CSF samples obtained from the younger normal control participants and the older participants without amyloid deposition, but not from the older participants with amyloid deposition. Significant circadian patterns were observed in the Aβ levels in CSF samples obtained from the younger control participants; however, circadian amplitudes decreased in both older participants without amyloid deposition and older participants with amyloid deposition. Aβ diurnal concentrations were correlated with the amount of sleep but not with the various activities that the participants participated in while awake.
  
  
  CONCLUSIONS
  A reduction in the linear increase in the Aβ levels in CSF samples that is associated with amyloid deposition and a decreased CSF Aβ diurnal pattern associated with increasing age disrupt the normal physiology of Aβ dynamics and may contribute to AD.
authors.affiliation: Department of Neurology, Washington University School of Medicine, 660 S Euclid, PO Box 8111, St Louis, MO 63110, USA.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Huang
authors.forename: Rachel
authors.initials: R
authors.lastname: Potter
authors.forename: Wendy
authors.initials: W
authors.lastname: Sigurdson
authors.forename: Anna
authors.initials: A
authors.lastname: Santacruz
authors.forename: Shirley
authors.initials: S
authors.lastname: Shih
authors.forename: Yo-El
authors.initials: YE
authors.lastname: Ju
authors.forename: Tom
authors.initials: T
authors.lastname: Kasten
authors.forename: John C
authors.initials: JC
authors.lastname: Morris
authors.forename: Mark
authors.initials: M
authors.lastname: Mintun
authors.forename: Stephen
authors.initials: S
authors.lastname: Duntley
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Bateman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000134:cerebrospinal fluid* / Q000473:pathology*; D000682:Amyloid / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D000814:Aniline Compounds; D016022:Case-Control Studies; D002490:Central Nervous System / Q000000981:diagnostic imaging / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D004569:Electroencephalography; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D058225:Plaque, Amyloid / Q000473:pathology*; D049268:Positron-Emission Tomography; D012890:Sleep; D013844:Thiazoles; D014741:Video Recording; D014851:Wakefulness
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D000682:Amyloid; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D013844:Thiazoles