We therefore analyzed plasma levels of the Aβ42/40 ratio, Aβ40, Aβ42, the pTau‐181/Aβ42 ratio, pTau‐181, NfL, and GFAP in a unique cohort of centenarians with cognitive abilities ranging from high‐performing to having initial symptoms of cognitive decline, of whom a subset agreed to post mortem brain donation. The gene discussed is GFAP; the disease is Mental deterioration.