MAPT and Parkinson disease: For example, α-synuclein in LBs and tau fibrils co-occur in the brains of up to 50% of patients with Alzheimer’s disease [47–49], tau pathology is documented in nearly half of patients with PD [50–52], and β-amyloid plaques are present in nearly 40% of patients with PD and 60–80% of patients with PDD or DLB [53].