title: Cerebrospinal fluid biomarkers in Alzheimer's disease: Diagnostic accuracy and prediction of dementia.
abstract: BACKGROUND
  Guidelines for the use of cerebrospinal fluid (CSF) biomarkers in the diagnosis of Alzheimer's disease (AD) establish that each laboratory must use internally qualified cutoff values. We determined the concentrations of biomarkers that discriminate cases from controls and combinations that predict the progression to dementia in a Brazilian cohort.
  
  
  METHODS
  Concentrations of amyloid-beta peptide (Aβ1-42), total tau (T-tau), and (181)Thr-phosphorylated-tau (P-tau) were determined in CSF samples from 184 older adults (68 mild cognitive impairment, 41 AD, 34 non-AD cognitive impairment, and 41 controls) by the INNO-BIA AlzBio3 assay.
  
  
  RESULTS
  Cutoff values discriminating AD from controls are as follows: Aβ1-42: 416.0 pg/mL (sensitivity [SE]: 83%, specificity (SP): 70%); T-tau: 76.7 pg/mL (SE: 82%, SP: 67%); P-tau: 36.1 pg/mL (SE: 83%, SP: 49%); Aβ1-42/P-tau <9.53 (SE: 88%, SP: 78%); and Aβ1-42/T-tau <4.13 (SE: 80%; SP: 80%). Combining values Aβ1-42 <416.5 pg/mL and Aβ1-42/P-tau <9.5 best predicted the conversion in 2 years (Cox regression: hazard ratio 7.24 [2.09-25.06], P = .002, SE: 74%, Sp: 73%).
  
  
  CONCLUSIONS
  Our findings are in line with most of the available evidence in this field; yet, our cutoff values are different from those derived from other laboratories.
authors.affiliation: Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Orestes V
authors.initials: OV
authors.lastname: Forlenza
authors.affiliation: Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Marcia
authors.initials: M
authors.lastname: Radanovic
authors.affiliation: Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Leda L
authors.initials: LL
authors.lastname: Talib
authors.affiliation: Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Ivan
authors.initials: I
authors.lastname: Aprahamian
authors.affiliation: Department of Mental Health, Faculty of Medicine, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Breno S
authors.initials: BS
authors.lastname: Diniz
authors.affiliation: Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden; UCL Institute of Neurology, London, UK.
authors.forename: Henrik
authors.initials: H
authors.lastname: Zetterberg
authors.affiliation: Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of Sao Paulo, Sao Paulo, SP, Brazil.
authors.forename: Wagner F
authors.initials: WF
authors.lastname: Gattaz
keywords: Alzheimer's disease; Amyloid-β; Biomarkers; Cerebrospinal fluid; Mild cognitive impairment; Tau protein