MAPT and Alzheimer disease: To address these questions, we investigated aberrant tau species associated with AD severity [9, 40, 57], including various pretangle forms such as p-tau, Cit-tau, and tau oligomers, as well as pretangle and mature MC-1-positive and PHF-1-positive tau tangle forms in postmortem retinal tissues from a cohort of individuals with MCI (due to AD), AD dementia, as compared to normal cognition (NC) and non-AD dementia (D-NAD) controls.