Investigating the Factor Structure of the Preclinical Alzheimer Cognitive Composite and Cognitive Function Index across Racial/Ethnic, Sex, and Aβ 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 β-amyloid (Aβ) 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 Aβ 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 Aβ− and 1309 were classified as Aβ+. 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 Aβ status. The one-factor model of the PACC and Cognitive Function Index demonstrated scalar measurement invariance across racial/ethnic, sex/gender, and Aβ 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 Aβ status groups examined in this study.