Winer JR, et al. - This cross-sectional study was performed to compare tau aggregation in patients with Parkinson's disease (PD) who were cognitively normal (PD-CN), patients with PD with mild cognitive impairment (PD-MCI), and healthy control participants. Furthermore, the researchers assessed the associations between β-amyloid (Aβ), tau, and cognition in patients with PD who did not have dementia. No difference in patterns of cortical Aβ and tau was observed in people with PD-CN, people with PD-MCI, and healthy older adults. Age, Aβ, and tau did not differentiate patients with PD-CN and PD-MCI. In both people with PD and healthy older adults, tau deposition was associated with Aβ status and age. Among people with PD who did not have dementia, cognitive deficits did not appear to reflect measureable Alzheimer's disease.