Interleukin-6 is associated with cognitive function: The Northern Manhattan Study

Inflammation has been linked to cognitive decline and dementia, but the mechanism for this is not clear, and few studies have included Hispanic and black subjects who may be at increased risk for these disorders. We performed a cross-sectional analysis of the association between inflammatory marker levels and cognition in the stroke-free population-based cohort of the Northern Manhattan Study. Mini Mental State Exam (MMSE) scores were the continuous outcome, and we adjusted for sociodemographic and vascular risk factors as well as subclinical atherosclerosis. Of the inflammatory markers, only interleukin (IL)-6 levels were associated with the MMSE. In univariate analysis, age, hypertension, diabetes, smoking, moderate alcohol use, total homocysteine, carotid intima media thickness, and body mass index were positively associated with IL-6 levels. Hispanic ethnicity, less than a high school education, hypertension, cardiac disease, and total homocysteine were associated with lower MMSE scores. In a multivariate linear regression model, IL-6 was negatively associated with MMSE score adjusting for sociodemographic and vascular risk factors. We conclude that IL-6 levels were negatively associated with performance on the MMSE in this multiethnic cohort. Adjusting for vascular disease and subclinical atherosclerosis did not attenuate the association, suggesting a direct effect on the brain.