The implications of different approaches to define AT(N) in Alzheimer disease

Neurology. 2020 May 26;94(21):e2233-e2244. doi: 10.1212/WNL.0000000000009485. Epub 2020 May 12.


Objective: To compare different β-amyloid (Aβ), tau, and neurodegeneration (AT[N]) variants within the Swedish BioFINDER studies.

Methods: A total of 490 participants were classified into AT(N) groups. These include 53 cognitively unimpaired (CU) and 48 cognitively impaired (CI) participants (14 mild cognitive impairment [MCI] and 34 Alzheimer disease [AD] dementia) from BioFINDER-1 and 389 participants from BioFINDER-2 (245 CU and 144 CI [138 MCI and 6 AD dementia]). Biomarkers for A were CSF Aβ42 and amyloid-PET ([18F]flutemetamol); for T, CSF phosphorylated tau (p-tau) and tau PET ([18F]flortaucipir); and for (N), hippocampal volume, temporal cortical thickness, and CSF neurofilament light (NfL). Binarization of biomarkers was achieved using cutoffs defined in other cohorts. The relationship between different AT(N) combinations and cognitive trajectories (longitudinal Mini-Mental State Examination scores) was examined using linear mixed modeling and coefficient of variation.

Results: Among CU participants, A-T-(N)- or A+T-(N)- variants were most common. However, more T+ cases were seen using p-tau than tau PET. Among CI participants, A+T+(N)+ was more common; however, more (N)+ cases were seen for MRI measures relative to CSF NfL. Tau PET best predicted longitudinal cognitive decline in CI and p-tau in CU participants. Among CI participants, continuous T (especially tau PET) and (N) measures improved the prediction of cognitive decline compared to binary measures.

Conclusions: Our findings show that different AT(N) variants are not interchangeable, and that optimal variants differ by clinical stage. In some cases, dichotomizing biomarkers may result in loss of important prognostic information.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / classification*
  • Alzheimer Disease / epidemiology*
  • Amyloid beta-Peptides / cerebrospinal fluid
  • Amyloid beta-Peptides / metabolism*
  • Aniline Compounds / metabolism
  • Benzothiazoles / metabolism
  • Biomarkers / cerebrospinal fluid
  • Biomarkers / metabolism
  • Brain / metabolism
  • Brain / pathology
  • Carbolines / metabolism
  • Case-Control Studies
  • Cognitive Dysfunction / epidemiology*
  • Female
  • Humans
  • Longitudinal Studies
  • Male
  • Mental Status and Dementia Tests / statistics & numerical data
  • Middle Aged
  • Nerve Degeneration / epidemiology*
  • Neurofilament Proteins / cerebrospinal fluid
  • Positron-Emission Tomography
  • Sweden / epidemiology
  • tau Proteins / cerebrospinal fluid
  • tau Proteins / metabolism*


  • Amyloid beta-Peptides
  • Aniline Compounds
  • Benzothiazoles
  • Biomarkers
  • Carbolines
  • Neurofilament Proteins
  • neurofilament protein L
  • tau Proteins
  • flutemetamol
  • 7-(6-fluoropyridin-3-yl)-5H-pyrido(4,3-b)indole