Cognitive screening biases in a secondary prevention Alzheimer's disease clinical trial.

INTRODUCTION: Alzheimer's disease (AD) prevention trials have multiple steps to identify cognitively unimpaired individuals with AD biomarker evidence. Cognitive/functional screening tests may be biased in ethnoracial minorities, impacting trial eligibility. METHODS: A total of 6669 participants screened for the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study were grouped by ethnoracial background and testing language. Ethnoracial/language differences in ineligibility reason, cognitive/functional test performance, and amyloid positivity rates were examined. RESULTS: Ethnoracial minorities were least likely to meet eligibility criteria. Patterns of incorrect Mini-Mental State Examination items and impaired Clinical Dementia Rating functional domains differed between ethnoracial/language groups, suggesting potential test biases. The Free and Cued Selective Reminding Test yielded more similar exclusion rates across groups than Logical Memory. Cognitive/functional screening biases may impact subsequent biomarker screening as amyloid positivity rates were lowest in ethnoracial minorities. DISCUSSION: Biases in cognitive/functional screening tests may be contributing to disproportionate exclusion of ethnoracial minorities in AD clinical trials.