Irwin et al. suggested that AD-type pathology (Aβ and tau-containing neurofibrillary tangles) combined with α-syn could have a synergistic role in PD-D, and the level of AD pathology was found to have a positive correlation with cognitive impairment (Irwin et al., 2012, 2013). The gene discussed is MAPT; the disease is Cognitive impairment.