Post-mortem studies showing the coexistence of amyloid and tau pathologies with LBs in synucleinopathies have led to investigating core Alzheimer’s disease (AD) biomarkers—amyloid beta 40 (Aβ40) and amyloid beta 42 (Aβ42) proteins, total tau, and phosphorylated tau proteins—in PD [54]. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.