Background: Researchers document bidirectional pathways linking peripheral inflammation and neural circuitries subserving emotion processing and regulation. To extend this work, we present results from two independent studies examining the relationship between inflammation and resting-state functional connectivity (rsFC), as measured by functional magnetic resonance imaging.
Methods: Study 1 involved 90 rural African American young adults, 25 years of age (52% female), and study 2 involved 82 urban African American youths, 13 to 14 years of age (66% female). Both studies measured circulating inflammatory biomarkers (C-reactive protein, interleukin 6, interleukin 10, tumor necrosis factor alpha), and the measures were averaged to form a composite. Study 2 also enumerated classical monocytes, a key leukocyte subpopulation involved in immune-to-brain signaling. All participants completed a resting-state functional magnetic resonance imaging scan.
Results: Consistent with our prediction, higher scores on the inflammatory composite were associated with lower rsFC within an emotion regulation network in study 1, controlling for sex. Study 2 replicated study 1, showing that higher scores on the inflammatory composite were associated with lower rsFC within the emotion regulation network, controlling for sex, age, and pubertal status, and found a similar pattern for rsFC within a central executive network. Study 2 also found that higher numbers of classical monocytes were associated with lower rsFC within both the emotion regulation and central executive networks. There was no relationship between rsFC in the anterior salience or default mode networks with inflammation in either study.
Conclusions: With these findings, we document relationships between peripheral inflammation and rsFC within an emotion regulation and central executive network and replicate these associations with the emotion regulation network across two independent samples.
Keywords: Inflammation; Mental health; Neuroscience; Physical health; Resting state; fMRI.
Copyright © 2019 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.