MAPT and Alzheimer disease: Cognitive impairment in DLB and PDD have been associated with CSF AD biomarkers (tau phosphorylated at threonine 181 [P‐tau181], total tau and Aβ42),10 and tau‐PET measures.11, 12 However, limited availability, cost, and invasiveness hamper global implementation in identifying AD pathology in clinical settings and clinical trials.