Inflammation and cognitive functioning in African Americans and Caucasians

To examine associations between inflammation and cognitive performance in African Americans and Caucasians.

The sample included 59 African Americans and 219 Caucasians ≥  50 years old who had a baseline visit at the Emory/Georgia Tech Center for Health Discovery and Well Being. Peripheral levels of inflammation (interleukin-6, interleukin-8, C-reactive protein, and tumor necrosis factor-α) were examined in relation to performance on tests of visual processing (Identify the Odd Pattern), attention (Digit Span Forward), visuomotor set shifting (Digit Symbol Substitution), verbal set shifting (Digit Span Backwards), and memory (Recall a Pattern).

Multiple regression models adjusting for potential demographic and vascular/metabolic confounders were conducted, with markers of inflammation included as either continuous or categorical (quartiles) variables. There were significant interactions between IL-8 and race for the Recall a Pattern (p = .006) and the Digit Symbol Substitution (p = .014) tests. Race-specific analyses (using a continuous variable for IL-8) demonstrated slower response times on the Recall a Pattern and Digit Symbol Substitution tests for African Americans but not for Caucasians. Categorical analyses among African Americans indicated that all of the top three quartiles of IL-8 were associated with slower reaction times on the Recall a Pattern test compared to the lowest quartile, while for Digit Symbol, the highest quartile of IL-8 was associated with the slowest cognitive performance.

These preliminary findings suggest a stronger association between IL-8 and cognitive performance in African Americans than Caucasians. This relationship should be further examined in larger samples that are followed over time.