Mood disturbance after infection.

Gunaratne, Pramudie; Lloyd, Andrew R; Vollmer-Conna, Ute

OBJECTIVE An aetiological link between acute infection and major depression has long been hypothesized, and is increasingly gaining recognition within contemporary literature. This review aims to examine the evidence for such a link, specifically between acute, self-limiting infection and major depression, and to summarize the current understanding of pathophysiological mechanisms underlying this link. METHODS Relevant articles were sourced via an online search of published literature from Embase, MEDLINE, PsycINFO and PubMed using a variety of search terms including mood disorder, depression, infection and inflammation. Additionally, a search for articles from the bibliographies of retrieved papers was conducted. RESULTS Findings from retrospective studies suggest an association between infection and subsequent mood disturbance, including major depression. This association has been confirmed by studies employing prospective observational or experimental challenge designs. The available evidence supports a multifactorial basis of vulnerability towards major depression in the context of acute infection. Genetic, neuroendocrine, autonomic and psychosocial factors may interact to potentiate the likelihood of a severe and prolonged depressive response to an immunological stressor in some individuals. CONCLUSION Mood disturbance is likely to have a host-protective role in the context of an acute sickness response to infection. However, this usually adaptive and reversible response may progress in some vulnerable individuals into a more sustained and severe pattern of behavioural and physiological changes of major depression. Further research is needed to delineate the factors that predispose, precipitate and perpetuate depression in the context of acute infective illness. Such insights will inform effective prevention and treatment strategies.