MAPT and early-onset autosomal dominant Alzheimer disease: Tau protein, a microtubule-associated protein has been found to be elevated in the CSF of patients suffering from Alzheimer's disease [15], as well as in patients with Lewy body dementia, corticobasal degeneration [61], and Creutzfeldt-Jakob disease [62] indicating that it is a marker of neuronal degeneration.