We found six highly reproducible principal components (PCs) within each diagnostic category (Table 2 and Supplementary Table 4): core AD, sTNFR1 (also sTNFR2, sVCAM1, sICAM1, TGFβ1), sTREM2, IL-6/IL-10, TGFβ (TGFβ2, TGFβ1), and IL-7/TNF-α, even though there were instances where some variables demonstrated diagnosis-specific loading (e.g., IP-10 on PC2 in the two groups with AD dementia). Here, TNF is linked to Alzheimer disease.