Participants were cognitively unimpaired or cognitively impaired (mild cognitive impairment or dementia) at baseline.<h4>Exposure</h4>Cerebrospinal fluid α-synuclein status determined by SAA and dichotomized as SAA negative or SAA positive.<h4>Main outcomes and measures</h4>Tau burden was quantified as standardized uptake value ratio (SUVr) in the medial temporal composite region of interest. The gene discussed is MAPT; the disease is Cognitive impairment.