Association between anti-inflammatory interleukin-10 and executive function in African American women at risk for Alzheimer's disease.

Introduction: African-Americans (AAs) are 64% more likely to be diagnosed with AD than non-Hispanic Whites. AAs with elevated AD biomarkers exhibit greater neurodegeneration in AD signature regions compared to non-Hispanic Whites with elevated AD biomarkers. This pilot trial examined whether normal or elevated plasma levels of interleukin (IL)-10 are associated with changes in executive function and short-term memory in AA women at risk for developing AD due to parental history.

Method: Observational study comparing groups with elevated and normal plasma IL-10 levels. Study included 31 AA women (age=58.9±8 years) with parental history of AD. Measures included inflammatory blood biomarkers, executive function and visuospatial short-term memory tests. Multivariate linear regression with adjustment for comorbidities, and Bonferroni corrections for multiple comparisons were used to compare groups. Effect sizes (Cohen's d) were generated. Using endpoints with moderate-large effects between groups, Pearson correlations determined associations between biomarker levels and cognitive performance.

Results: The elevated IL-10 group performed worse on the Trail-Making Test proportional score ((B-A)/A) (effect size ( d =-0 .87 (-1.6, -.1)). Moderate effects with large confident intervals were noted in inhibition, set-switching, and body position spatial memory. Significant differences between groups in levels of other inflammatory markers were noted, including IL-7 ( p =0.002) and interferon γ ( p =0.02). IL-7 remained significant after Bonferroni correction. Correlation matrices revealed moderate-large, significant correlations (yet with wide confidence intervals) between levels of IL-10 and IL-9 with BPST total correct trials, and between interferon γ and delayed recall.

Conclusions: Interleukins may incite inflammation, leading to impaired aspects of executive function and short-term memory in this sample of African American women at risk for developing AD. This research provides effect sizes that will be used to power future research that will further investigate the relationship between inflammation, AD biomarkers, and cognitive function in an understudied population.