Brain, behavior, and immunity
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Epidemiological data demonstrate an association between systemic low-grade inflammation defined as 2- to 3-fold increases in circulating inflammatory mediators and age-related decline in cognitive function. However, it is not known whether small elevations of circulating cytokine levels cause direct effects on human neuropsychological functions. We investigated changes in emotional, cognitive, and inflammatory parameters in an experimental in vivo model of low-grade inflammation. ⋯ The neutrophil count increased and the lymphocyte count declined. In this model, low-dose endotoxemia did not affect cognitive performance significantly but declarative memory performance was inversely correlated with cytokine increases. In conclusion, our findings demonstrate a negative association between circulating IL-6 and memory functions during very low-dose endotoxemia independently of physical stress symptoms, and the hypothalamo-pituitary-adrenal axis.