Single plasma measurements of Ab42/Ab40, GFAP, NfL, p-tau181 and p-tau217, taken while participants were cognitively unimpaired, were linked to 2,293 subsequent MRI scans and to later diagnosis in 818 members of the Baltimore Longitudinal Study of Aging, of whom 104 converted, 74 of them to Alzheimer's disease. The markers p-tau181, Ab42/Ab40 and p-tau217 were associated with incident mild cognitive impairment or dementia due to Alzheimer's disease but not other causes, while GFAP was associated with both. No biomarker was associated with change in the brain-age atrophy score or with subcortical, diffuse cortical or perisylvian atrophy patterns, in a preprint not yet peer reviewed.
Why it is interesting: Separates what the blood markers detect, atrophy specific to Alzheimer's disease, from general brain ageing, in people tested while still cognitively unimpaired.