From inflammation to sickness and depression: when the immune system subjugates the brain.

Integrative Immunology & Behavior, Department of Animal Sciences, College of Agricultural, Consumer and Environmental Sciences, University of Illinois, Urbana-Champaign, Illinois 61801, USA.
Nature Reviews Neuroscience (Impact Factor: 31.38). 02/2008; 9(1):46-56. DOI: 10.1038/nrn2297
Source: PubMed

ABSTRACT In response to a peripheral infection, innate immune cells produce pro-inflammatory cytokines that act on the brain to cause sickness behaviour. When activation of the peripheral immune system continues unabated, such as during systemic infections, cancer or autoimmune diseases, the ensuing immune signalling to the brain can lead to an exacerbation of sickness and the development of symptoms of depression in vulnerable individuals. These phenomena might account for the increased prevalence of clinical depression in physically ill people. Inflammation is therefore an important biological event that might increase the risk of major depressive episodes, much like the more traditional psychosocial factors.

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