Investigating the Factor Structure of the Preclinical Alzheimer Cognitive Composite and Cognitive Function Index across Racial/Ethnic, Sex, and A Status Groups in the A4 Study

Background: Disparities in Alzheimer's disease (AD) are well-documented among different racial/ethnic groups and between sex/genders. Neuropsychological assessment provides important information about cognitive changes and can offer valuable insights into disparities. However, neuropsychological measures must be comparable across racial/ethnic and sex/gender groups to accurately interpret disparities.Objectives: To evaluate measurement invariance (equivalence) of the Preclinical Alzheimer Cognitive Composite (PACC) and the Cognitive Function Index across racial/ethnic, sex/gender, and beta-amyloid (A beta) status groups.Design, Setting, Participants: Cross-sectional analysis of screening data from the Anti-Amyloid in Asymptomatic AD (A4) Study. The study enrolled participants aged 65-85 from sites across the United States, Canada, Australia, and Japan.Measurements: Participants completed the PACC and the Cognitive Function Index. Participants classified as cognitively normal also underwent a Positron Emission Tomography (PET) scan to determine A beta status.Results: Participants self-identified as non-Hispanic White (n=5241), non-Hispanic Black (n=267), Asian (n=228), or Hispanic White (n=225) as well as male (n=2885) or female (n=3076). Among those who underwent a PET scan, 3115 were classified as A beta- and 1309 were classified as A beta+. We found support for a one-factor model for both the PACC and Cognitive Function Index across the full sample and in samples stratified by race/ethnicity, sex/gender, and A beta status. The one-factor model of the PACC and Cognitive Function Index demonstrated scalar measurement invariance across racial/ethnic, sex/gender, and A beta status groups.Conclusions: Our findings suggest that performance on the PACC and Cognitive Function Index can be compared across the racial/ethnic, sex/gender, and A beta status groups examined in this study.