By Dr. Mercola

Depression is increasingly recognized as a problem rooted in chronic inflammation. While other factors may also be involved, inflammation can have a profound impact on your mental health.

The study of these connections is known as psychoneuroimmunology, i.e., the impact of inflammation on behavior. As noted in one 2012 study in the journal Neuropsychopharmacology:1

“Elevated biomarkers of inflammation, including inflammatory cytokines and acute-phase proteins, have been found in depressed patients, and administration of inflammatory stimuli has been associated with the development of depressive symptoms.

Data also have demonstrated that inflammatory cytokines can interact with multiple pathways known to be involved in the development of depression, including monoamine metabolism, neuroendocrine function, synaptic plasticity, and neurocircuits relevant to mood regulation …

Psychosocial stress, diet, obesity, a leaky gut and an imbalance between regulatory and pro-inflammatory T cells also contribute to inflammation and may serve as a focus for preventative strategies relevant to both the development of depression and its recurrence.”

Inflammation and Depression

In this model, depression is the result of your body’s attempts to protect itself from an inflammatory response, and involves hormones and neurotransmitters. Depressive symptoms most strongly associated with chronic inflammation include flat mood, slowed thinking, avoidance, alterations in perception and metabolic changes.2

Cytokines in your blood, or inflammatory messengers such as CRP, interleukin-1 (IL-1), interleukin-6 (IL-6) and TNF-alpha are all predictive of3 and correlate4 to depression.

For example, in melancholic depression, bipolar disorder and postpartum depression, white blood cells called monocytes express pro-inflammatory genes that provoke secretion of cytokines.5 At the same time, cortisol sensitivity goes down, and cortisol is a stress hormone that buffers against inflammation.

Together, these inflammatory agents transfer information to your nervous system, typically by stimulating your vagus nerve, which connects your gut and brain.6

During inflammatory states, brain cells called microglia are activated. When this happens, an enzyme called indoleamine 2 3-dioxygenase (IDO) directs tryptophan away from the production of serotonin and melatonin, instructing it instead to produce an NMDA (an amino acid derivative) agonist called quinolinic acid, which can trigger anxiety and agitation.7 …continue reading at