Taking the A Train? Limited Consistency of Aβ₄₂ and the Aβ_42/40 Ratio in the AT(N) Classification

Article type: Short Communication

Authors: Gouilly, Dominique^{a; *} | Tisserand, Camille^b | Nogueira, Leonor^c | Saint-Lary, Laura^d | Rousseau, Vanessa^d | Benaiteau, Marie^b | Rafiq, Marie^b | Carlier, Jasmine^b | Milongo-Rigal, Emilie^b | Pagès, Jean-Christophe^c | Pariente, Jérémie^{a; b}

Affiliations: [a] Toulouse Neuroimaging Center, Toulouse, France | [b] Department of Cognitive Neurology, Epilepsy and Movement Disorders, CHU Toulouse Purpan, France | [c] Department of Cell Biology and Cytology, CHU Toulouse Purpan, France | [d] Center of Clinical Investigation, CHU Toulouse Purpan (CIC1436), France

Correspondence: [*] Correspondence to: Dominique Gouilly, Toulouse Neuroimaging Center, Toulouse, France; Unité ToNIC, UMR 1214, CHU PURPAN –Pavillon BAUDOT, Place du Dr Joseph Baylac, 31024, Toulouse, cedex 3, France. Tel.: +33562746190; E-mail: dominique.gouilly@inserm.fr.

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of the dichotomized amyloid status (A+/A–) in 363 patients tested for Alzheimer’s disease biomarkers after Aβ42 was superseded by the Aβ42/40 ratio.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

DOI: 10.3233/JAD-210236

Journal: Journal of Alzheimer's Disease, vol. 83, no. 3, pp. 1033-1038, 2021