Evaluation of CSF-tau and CSF-Abeta42 as diagnostic markers for Alzheimer disease in clinical practice

Arch Neurol. 2001 Mar;58(3):373-9. doi: 10.1001/archneur.58.3.373.


Objective: To evaluate the diagnostic potential of cerebrospinal fluid (CSF) levels of tau and beta-amyloid protein ending at amino acid 42 (Abeta42) as biomarkers for Alzheimer disease (AD) in clinical practice.

Design: A 1-year prospective study.

Setting: Community population-based sample of all consecutive patients admitted for investigation of cognitive symptoms to the Piteå River Valley Hospital, Piteå, Sweden.

Patients: A total of 241 patients with probable AD (n = 105), possible AD (n = 58), vascular dementia (n = 23), mild cognitive impairment (n = 20), Lewy body dementia (n = 9), other neurological disorders (n = 3), and psychiatric disorders (n = 5) and nondemented individuals (n = 18).

Main outcome measures: Cerebrospinal fluid tau and CSF-Abeta42 were assayed each week as routine clinical neurochemical analyses. Sensitivity and specificity were defined using the regression line from 100 control subjects from a multicenter study. Positive and negative predictive values were calculated for different prevalence rates of AD.

Results: We found increased CSF-tau and decreased CSF-Abeta42 levels in probable and possible AD. Sensitivity was 94% for probable AD, 88% for possible AD, and 75% for mild cognitive impairment, whereas specificity was 100% for psychiatric disorders and 89% for nondemented. Specificity was lower in Lewy body dementia (67%) mainly because of low CSF-Abeta42 levels and in vascular dementia (48%) mainly because of high CSF-tau levels. Sensitivity for CSF-tau and CSF-Abeta42 increased in patients with AD possessing the ApoE epsilon4 allele, approaching 100%. At a prevalence of AD of 45%, the positive predictive value was 90% and the negative predictive value was 95%.

Conclusions: Cerebrospinal fluid tau and CSF-Abeta42 have so far been studied in research settings, under conditions providing data on the optimal performance. We examined a prospective patient sample, with assays run in clinical routine, giving figures closer to the true performance of CSF-tau and CSF-Abeta42. The predictive value for AD was greater than 90%. Therefore, these biomarkers may have a role in the clinical workup of patients with cognitive impairment, especially to differentiate early AD from normal aging and psychiatric disorders.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / cerebrospinal fluid*
  • Alzheimer Disease / diagnosis*
  • Amyloid beta-Peptides / cerebrospinal fluid*
  • Biomarkers / cerebrospinal fluid
  • Cognition Disorders / cerebrospinal fluid
  • Cognition Disorders / diagnosis
  • Female
  • Humans
  • Male
  • Middle Aged
  • Peptide Fragments / cerebrospinal fluid*
  • Predictive Value of Tests
  • Prospective Studies
  • Regression Analysis
  • Sensitivity and Specificity
  • tau Proteins / cerebrospinal fluid*


  • Amyloid beta-Peptides
  • Biomarkers
  • Peptide Fragments
  • amyloid beta-protein (1-42)
  • tau Proteins