Table 3.
Number of participants classified at each stage of preclinical AD based on the two staging systems
| Staging system based on number of abnormal biomarkersb
|
|||||
|---|---|---|---|---|---|
| 0 Biomarkers | 1 Biomarker | 2 Biomarkers | 3 Biomarkers | ||
| NIA-AA Staging Systema | Stage 0 | 55 | – | – | – |
| Stage 1 | – | 23 | – | – | |
| Stage 2 | – | – | 89 | – | |
| Stage 3 | – | – | – | 25 | |
| SNAPc | – | 91 | 9 | – | |
| Unclassifiedd | – | 13 | 7 | – | |
Note. NIA-AA = National Institute on Aging–Alzheimer’s Association; SNAP = suspected non-AD pathophysiology.
a
Staging system based on the biomarkers/cognitive markers an individual possesses and requires a specific temporal order (i.e., amyloidosis first, then neurodegeneration, then subtle cognitive decline).
b
Staging system based on the number of biomarkers/cognitive markers an individual possesses without regard for their temporal order of occurrence.
c
SNAP participants had neurodegeneration with normal amyloid levels.
d
Unclassified participants had subtle cognitive/functional decline with no neurodegeneration.