title: Cerebrospinal fluid Aβ and tau level fluctuation in an older clinical cohort.
abstract: OBJECTIVE
  To determine whether cerebrospinal fluid (CSF) biomarkers for Alzheimer disease fluctuate significantly over time in a cohort of older, mildly symptomatic individuals.
  
  
  METHODS
  Biomarker validation in a clinical cohort.
  
  
  METHODS
  University hospital inpatient unit.
  
  
  METHODS
  Ten patients admitted for CSF drainage for diagnostic purposes.
  
  
  METHODS
  The CSF levels of Aβ1-40, Aβ1-42, tau, and phosphorylated tau on threonine 181 (p-tau(181)) were measured every 6 hours for 24 or 36 hours.
  
  
  RESULTS
  The mean coefficient of variation values for each biomarker assessed in our 10 patients were 5.5% (95% CI, 3.8%-10.0%) for Aβ1-42, 12.2% (9.0%-24.2%) for Aβ1-40, 8.2% (5.7%-15.1%) for total tau, and 11.9% (8.5%-23.0%) for p-tau(181). These values are only slightly higher than the variability in the assay. In addition, no significant circadian fluctuation in any Alzheimer disease biomarker was observed given the limitations of our sampling frequency.
  
  
  CONCLUSIONS
  In a cohort of elderly patients, little fluctuation in the levels of important Alzheimer disease biomarkers in lumbar CSF is seen as a function of time.
authors.affiliation: Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Abhay
authors.initials: A
authors.lastname: Moghekar
authors.forename: Joshua
authors.initials: J
authors.lastname: Goh
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Marilyn
authors.initials: M
authors.lastname: Albert
authors.forename: Richard J
authors.initials: RJ
authors.lastname: O'Brien
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002940:Circadian Rhythm / Q000502:physiology; D003072:Cognition Disorders / Q000134:cerebrospinal fluid; D015331:Cohort Studies; D005260:Female; D020233:Gait Disorders, Neurologic / Q000134:cerebrospinal fluid; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D015203:Reproducibility of Results; D016875:tau Proteins / Q000134:cerebrospinal fluid*
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D016875:tau Proteins