MAPT and Parkinson disease: Within the field of neurodegenerative biomarkers, three CSF and plasma markers—beta-amyloid 1-42 (Aβ42), total tau (T-tau), and hyperphosphorylated tau (P-tau) protein—have gained significant attention for their diagnostic accuracy for AD (Olsson et al., 2016; Papaliagkas et al., 2023; Verberk et al., 2018), followed by PD (Vijiaratnam and Foltynie, 2023; Liu et al., 2015) and all-cause dementia (Hosoki and Sachdev, 2024).