Taken together, our results indicate changes in plasma amyloid-β1-42/1-40, p-tau181 and GFAP levels to be present already in very early stages of Alzheimer’s disease development, and that longitudinal, amyloid-β status-dependent changes in plasma p-tau181 and GFAP reflect disease progression in this pre-clinical stage. Here, GFAP is linked to early-onset autosomal dominant Alzheimer disease.