MAPT and early-onset autosomal dominant Alzheimer disease: Recent studies even propose that the final step in neurodegeneration is the pathological cerebral aggregation of toxic brain metabolism byproducts caused by disrupted clearance of these waste products, such as the deposition of amyloid-β 1–42 and Tau in Alzheimer’s disease and α-synuclein in Parkinson’s disease [22, 23].