African ancestry APOE e4 non-carriers with higher educational attainment are resilient to Alzheimer disease pathology-specific blood biomarker pTau181.

Abstract

Cognitive and functional abilities in individuals with Alzheimer disease (AD) pathology (ADP) show greater than expected variability. While most individuals show substantial impairments in these abilities, a considerable number show little or no impairments. Factors contributing to this variability are not well understood. For instance, multiple studies have shown that higher levels of education are associated with reduced cognitive impairments among those with ADP. However, it remains unclear whether higher levels of education are associated with functional impairments among those with ADP. We studied 410 AA individuals with advanced levels of pTau181 (a biomarker for ADP; individuals as those having log10(pTau181) level greater than one standard deviation above the mean) to determine whether EA (categorized as low EA for individuals with [≤] 8 years of education and high EA for those with >8 years) promotes functional resilience and whether this effect varies between APOE {varepsilon}4 carriers and non-carriers. We used the four non-memory components of the Clinical Dementia Rating (CDR) to create a composite score (CDR-FUNC) to evaluate functional difficulties (scored from 0=no impairment to 12=severe). We employed the non-parametric Mann-Whitney U test to assess the relationship between EA and CDR-FUNC in advanced levels of pTau181 individuals. The results showed that EA promotes resilience to functional problems in AA individuals with advanced levels of pTau181, such that individuals with high EA are more likely to have better functional ability compared to those with lower EA (W=730.5, p=0.0007). Additionally, we found that the effect of high EA on functional resilience was stronger in {varepsilon}4 non-carriers compared to {varepsilon}4 carriers (W=555.5, p=0.022). This study extends the role of cognitive reserve and EA to functional performance showing that cognitive reserve influences the association between ADP burden and functional difficulties. Interestingly, this protective effect seems less pronounced in carriers of the strong genetic risk allele {varepsilon}4. The results highlight the intricate interplay of genetic and non-genetic factors in AD progression, suggesting a need for more personalized strategies to manage functional decline in AD.