Can Having Amyloid-Positive and Tau-Negative Biomarkers Mean That Someone Has Alzheimer Disease?

Being amyloid-positive and tau-positive (A+T+) in the amyloid-tau-neurodegeneration (ATN) classification scheme represents underlying Alzheimer disease (AD). In this study, researchers examined whether participants in three cohorts who were amyloid-positive and tau-negative (A+T−) on cerebrospinal fluid (CSF) analysis had AD at autopsy. Each cohort had different cut-off points for amyloid and tau positivity in CSF based on clinical or autopsy diagnosed AD.

There were 43 to 92 participants in each cohort (21%–49% female). Time between CSF collection and death ranged from 2 to 5 years, 18–28% were classified as A+T−, and 46% to 91% had pathologically confirmed AD. At autopsy, all of the A+T+ participants and 50% to 73% of the A+T− participants…