MAPT and Alzheimer disease: In this study we evaluated both the diagnostic accuracy and the capability in predicting cognitive decline of CSF AD biomarkers (Aβ42, t-tau, p-tau and Aβ42/t-tau ratio) and α-syn species (t-α-syn, o-α-syn and o/t-α-syn ratio) in PD patients and neurological controls with a median follow up duration of 3 years.