More recently, it was suggested that a final common pathway to dementia disease may be the pathological cerebral aggregation of toxic by-products of brain metabolism caused by impaired cerebral clearance of these waste products, e.g., deposition of amyloid-β 1–42 and Tau in Alzheimer’s disease and α-synuclein in Parkinson’s disease [57]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.