Relative importance of multimodal risk factors to discriminate memory trajectories: Similarities and differences across ethnoracial groups in cognitively normal older adults

Abstract Background Inequalities in dementia incidence and heterogeneities observed on memory decline are present across ethnic/racial groups. Research suggests that inequities in risk/protective factors contribute towards these differences. We examine risk factors across multiple domains to identify those that best discriminate differences in memory trajectories across ethnoracial groups. Method We used an ethnoracially diverse longitudinal cohort of cognitively normal older adults (n = 299; mean age = 73.47 (6.90) years; 63.9% female) from the University of California, Davis‐Alzheimer’s Disease Research Center. First, we applied latent class growth analysis to objectively classify memory trajectories into distinct latent groups across a maximum of 10 follow‐ups. Second, we used random forest analyses (RFA) to examine relative importance of 22 risk/protective factors from seven domains (demographic, genetic, brain morphometry, plasma and functional biomarkers, psychological and lifestyle factors) to discriminate low/high memory performers as stratified by three ethnoracial groups (African Americans [AA; n = 111]; Hispanics [n = 108], Whites [n = 66]). Result First, we observed that four latent classes (low, intermediate, high, very high) best represented memory trajectories (Figure 1). Second, for our RFA analyses, we collapsed low and intermediate groups to a low group (n = 136; 40.4% AA, 25.6% Hispanics, 28.8% Whites), and high and very high to a high performing group (n = 148; 34.6% AA, 50% Hispanics, 15.4% Whites). High memory class was predicted (Figure 2) in AA by lower smoking years, lower Functional Assessment Questionnaire (FAQ), younger age, higher education, lower neurofilament light (NfL), Apolipoprotein E non‐carriers, low neuropsychiatric inventory (NPI) severity, men, and higher hippocampal volume (AUC = 0.73); in Hispanics with men, lower FAQ, lower Geriatric Depression Scale (GDS), smaller third ventricle, larger hippocampal volume, lower NPI severity, smaller lateral ventricle, and lower NfL (AUC = 0.86); and in Whites, with lower FAQ, higher education, higher alcohol use frequency, lower NfL, lower GDS, smaller lateral ventricles, and low white matter hyperintensities (AUC = 0.82). Conclusion We observed similarities and differences in predictors to discriminate low versus high memory performers in three ethnoracial groups. Identifying relative importance of risk factors will promote the integration of multimodal risk factors across ethnoracial groups to develop novel and complex risk profiles leading to early detection and identification of asymptomatic or preclinical older adults.