MAPT and early-onset autosomal dominant Alzheimer disease: However, there is mounting evidence that suggests AD and PD pathologies are significantly overlapped presumably due to synergistic interactions between tau and α-synuclein, highlighting the complexity of Alzheimer’s diseases and related dementia (ADRD) pathogenesis (Clinton et al., 2010; Moussaud et al., 2014; Castillo-Carranza et al., 2018).