Taking the A Train? Limited Consistency of Aβ42 and the Aβ42/40 Ratio in the AT(N) Classification

J Alzheimers Dis. 2021;83(3):1033-1038. doi: 10.3233/JAD-210236.

Abstract

The consistency of cerebrospinal fluid amyloid-β (Aβ)42/40 ratio and Aβ42 has not been assessed in the AT(N) classification system. We analyzed the classification changes of the dichotomized amyloid status (A+/A-) in 363 patients tested for Alzheimer's disease biomarkers after Aβ42 was superseded by the Aβ42/40 ratio. The consistency of Aβ42 and the Aβ42/40 ratio was very low. Notably, the proportions of "false" A+T-patients were considerable (74-91%) and corresponded mostly to patients not clinically diagnosed with Alzheimer's disease. Our results suggest that the interchangeability of Aβ42/40 ratio and Aβ42 is limited for classifying patients in clinical setting using the AT(N) scheme.

Keywords: Alzheimer’s disease; amyloid; cerebrospinal fluid; lumbar puncture.

Publication types

  • Letter

MeSH terms

  • Aged
  • Alzheimer Disease / classification
  • Amyloid beta-Peptides / cerebrospinal fluid*
  • Biomarkers / cerebrospinal fluid*
  • Cognitive Dysfunction / cerebrospinal fluid*
  • Humans
  • Peptide Fragments / cerebrospinal fluid*
  • Terminology as Topic*
  • tau Proteins / cerebrospinal fluid

Substances

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