Spearman’s rank-order correlation in PD cases between the pathological proteins in each brain region revealed a consistent association between α-synuclein and tau in all the examined brain regions, most strongly in the amygdala (Rho = 0.575, p = 0.003) and prefrontal cortex (Rho = 0.602, p = 0.003) (Table 2). This evidence concerns the gene MAPT and Parkinson disease.