By comparing the plasma of non‐AD dementia cases (n = 28), patients with AD (n = 86), preclinical AD (n = 169), and NCIs (n = 232), they found that PAbs‐BACE1 were highest in clinical AD patients, and that it exacerbated amyloid deposition in the brain, tau hyperphosphorylation and neurodegeneration. Here, BACE1 is linked to Alzheimer disease.