Inflammation and Cognition in Bipolar Disorder: Diverging Paths of Interleukin-6 and Outcomes

Bipolar disorder (BD) may present with neurocognitive dysfunction due to inflammatory alterations through different biological pathways. However, findings are not consistent regarding the patterns of neurocognitive dysfunction and elevation of inflammatory biomarkers during the different mood phases. Therefore, we aimed to determine associations between inflammatory biomarkers, neurocognitive functioning, and clinical outcomes in patients with BD in euthymia. We conducted a cross-sectional study including 109 adults. Serum levels of interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), neurocognitive parameters (ACER), number of suicide attempts (SA), and hospitalizations (NH) were measured. We found negative and moderate correlations between IL-6 and ACER total score, language, visuospatial abilities, and orientation/attention. There was a positive and moderate correlation between IL-6 and NH. IL-6 significantly predicted ACER total score, language, memory, orientation/attention, visuospatial abilities, and NH. Overall, IL-6 had an inverse association with neurocognition and clinical variables, whereas hs-CRP did not play a role. Here we demonstrate that IL-6 predicts neurocognitive functioning in adults with BD. BD may be a biological model for studying the relationship between inflammation and neurocognition in severe psychiatric disorders. Prospective studies at different mood phases of the disease must be conducted.