We aimed to develop individualized predictions for risk of developing any-cause dementia and Alzheimer’s disease (AD) dementia, in individuals with subjective cognitive decline (SCD) or mild cognitive impairment (MCI), using plasma phosphorylated-tau-181 (pTau181), phosphorylated-tau-217 (pTau217; in a subset), amyloid beta1-42/1–40 (Aβ42/40), glial fibrillary acidic protein (GFAP) and/or neurofilament light (NfL). The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.