INTERSECTIONALITY BETWEEN SEX AND RACE ON SEMANTIC MEMORY TRAJECTORIES OF BLACK AND NON-HISPANIC WHITE OLDER ADULTS

Abstract

Previous research has demonstrated differences in cognitive trajectories leading to Alzheimer's disease (AD) across racial/ethnic groups, as well as sex groups; however, very few studies have examined how race/ethnicity and sex intersect to affect cognitive trajectories of older adults. The purpose of this study was to examine how race/ethnicity and sex jointly and simultaneously determine semantic memory trajectories among Black and NHW female and male older adults who participated in the National Alzheimer's Coordinating Center (NACC) Uniform Data Set (UDS). Non-Hispanic White (NHW; n=5,034) and Black (BLK; n=865) female and male NACC participants age 65 and older who were non-demented at baseline were included in the current analyses. BLK participants had lower levels of educational attainment and were significantly younger at baseline compared to NHW participants. Age-and education-corrected semantic memory scores were derived from immediate and delayed trials of the Logical Memory subtest and Animal and Vegetable Naming Semantic Fluency subtests. Growth mixture models (GMMs) with multiple groups were used to estimate semantic memory trajectories over five years for each racial group. Growth factors were regressed on the binary variable sex to assess whether race moderated the relationship between sex and semantic memory over time. Three latent trajectory classes were identified, representing High-Stable (n = 1,999, 34%), Low-Stable (n = 2,675, 46%), and Decliner (n = 1,168, 20%). Participants in the BLK group tended to have lower initial semantic memory scores across classes; however, BLK participants in the Decliner class demonstrated a slower rate of decline over time compared to NHW Decliners. Being female was associated with higher baseline scores across racial groups. For the BLK decliner class, female sex was associated with more rapid decline in semantic memory over time. Failure to examine the relationship between sex and race/ethnicity on cognitive trajectories raises the potential of obscuring important differences in the onset and course of dementia. The current study takes an important step in understanding racial/ethnic disparities in trajectories to dementia. Future research can build from the current findings and determine how biological and socio-cultural risk factors shape cognitive trajectories over time.