The Relationship Between Pain, Inflammation and Depression

In August of 2014, Chris Kresser wrote an article in which he suggested that depression is not a disease of the brain, but rather a symptom of chronic inflammation. He based this assertion on a theory called Immune Cytokine Model of Depression which states that depression is a multifaceted sign of chronic immune system activation.

A recently published study proposal entitled Pain, Depression and Inflammation: Are Interconnected Causative Factors Involved? shows that researchers are willing to look further into this theory. This study’s abstract, which was proposed by BE Leonard of the Department of Pharmacology at the National University of Ireland in Galway, was published in the medical journal, Modern trends in pharmacopsychiatry.

Leonard writes: “The purpose of this review is to examine the role of chronic inflammation as a common mediator of these co-morbidities. Dysfunctional bidirectional pathways between the brain and the immune, endocrine and neurotransmitter systems have been extensively described and implicated in pain and psychiatric disorders. This short review therefore accesses the evidence in favour of the psychoneuroendocrine hypothesis of psychiatric disorders under three main headings: (1) by illustrating how different types of stress play a crucial role in initiating chronic inflammation in major depression, (2) by accessing the evidence that pain is frequently an important component of, and an initiator of, depression, and (3) considering the evidence that chronic inflammation provides an important link between chronic pain and depression, and the possible cellular mechanisms involved in this process. By understanding the critical role that chronic inflammation plays in pain and depression, novel approaches to the development of drugs may emerge that offer improvements in treatment.”