Exploring the Link Between Persistent Infection, Inflammation, and Mood Disorders
By Tori Rodriguez, MA, LPC
May 25, 2018
Mood disorders affect more than 20% of adults in the United States aged 18 to 49 years.1 Extensive research has explored the genetic and behavioral underpinnings of these disorders, and more recently, studies have begun to investigate links between the immune system and mood regulation. Previous findings indicate that inflammation can lead to “sickness behavior” characterized by depressive symptoms such as anhedonia and fatigue.2,3 Inflammation has also been found to play a major role in glutamatergic neurotransmission involved in mood regulation in depression and bipolar disorder.4-6
“Specifically, microglia in the brain are activated by inflammatory cytokines that cross the blood-brain barrier, altering astroglial function such that these cells produce increased levels of cytokines as well as glutamate, contributing to enhanced tryptophan metabolism via the indoleamine 2,3-dioxygenase pathway,” wrote the authors of a recent study published in Brain, Behavior, and Immunity.7 “Imbalances in the metabolites of kynurenine which serve as either N-methyl-D aspartate agonists or antagonists and decreased serotonin production, in turn, may contribute to the onset of manic and depressive symptoms.”
It has been proposed that inflammation stemming from persistent pathogens may influence the development of mood disorders to a greater extent than inflammation resulting from acute infections. For example, 1 such pathogen is Helicobacter pylori, which has been implicated in gastrointestinal disorders and dysregulation of the gut-brain axis.8 A growing body of evidence also supports the role of interactions at the gut-brain axis in regulation of mood.9-11
In the current study, Dr Simanek and colleagues analyzed data from the National Health and Nutrition Examination Survey III to examine associations between mood disorders and persistent pathogens in individuals aged 15 to 39 years who had been assessed for a lifetime history of major depression, dysthymia, and/or bipolar disorder… Read the full article on Psychiatry.com.