Combination assay of CSF tau, A beta 1-40 and A beta 1-42(43) as a biochemical marker of Alzheimer's disease

J Neurol Sci. 1998 Jun 30;158(2):134-40. doi: 10.1016/s0022-510x(98)00122-1.


Cerebrospinal fluid samples from a total of 157 subjects consisting of 55 patients with sporadic Alzheimer's disease (AD), 34 normal controls, 23 patients with non-AD dementia, and 45 with other neurological diseases were examined by ELISA of tau, A beta 1-40, and A beta 1-42(43). The AD group had a significantly higher level of tau than the normal control group (P < 0.001), and the diagnostic sensitivity was 31% and specificity was 94%. CSF A beta 1-40 levels did not show any significant differences. Although the level of A beta 1-42(43) was decreased significantly in the AD group compared to the control group (P < 0.005), the overlap of A beta 1-42(43) levels among all groups meant that none of the AD samples exceeded the cut-off value, the mean 2SD of normal control subjects. Reduction of A beta 1-42(43) levels in AD resulted in a significant increase in the ratio of A beta 1-40 to A beta 1-42(43) (A beta ratio) as an improved marker. The diagnostic sensitivity and specificity of A beta ratio were 51% and 82% respectively. The three indexes, using the tau level and A beta ratio (tau or A beta ratio, deviation score and tau x A beta ratio), showed better sensitivity (58%, 67%, 69%) and specificity (82%, 86%, 88%) than previously reported methods. Combination assay for CSF tau, A beta 1-40 and A beta 1-42(43) in CSF is a biological marker of AD and may be useful to biochemically monitor subjects under treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / cerebrospinal fluid*
  • Amyloid beta-Peptides / cerebrospinal fluid*
  • Biomarkers
  • Dementia / cerebrospinal fluid
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nervous System Diseases / cerebrospinal fluid
  • Peptide Fragments / cerebrospinal fluid*
  • Reference Values
  • tau Proteins / cerebrospinal fluid*


  • Amyloid beta-Peptides
  • Biomarkers
  • Peptide Fragments
  • amyloid beta-protein (1-40)
  • amyloid beta-protein (1-42)
  • amyloid beta-protein (1-43)
  • tau Proteins