MAPT and Parkinson disease: Metabolic waste proteins, such as amyloid, tau, and synuclein, can be removed by the glymphatic system, and its impairment can lead to pathological accumulation of metabolic wastes that lead to neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and traumatic brain encephalopathy [12,13,14,15,16].