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

Alzheimer's disease (AD) prevention trials have multiple screening steps to identify cognitively unimpaired individuals with AD biomarker evidence. Cognitive/functional screening tests may be biased in underrepresented groups, thereby impacting trial eligibility.

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.

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 groups excluded for impaired cognition/function, suggesting 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.

Biases in cognitive/functional screening tests may disproportionately exclude ethnoracial minorities in AD prevention trials.