Depression: An Inflammatory Disease?

Written by on August 29, 2014 in Insight - No comments

The tragic and untimely death of actor/comedian Robin Williams has catapulted the subject of depression once again into media, and into the forefront of American consciousness. The development of SSRI’s and SNRI’s was an enormous breakthrough in the treatment of depression, yet still, there is little known about the mechanism of the illness, and more effective treatments.

DepressionWEBThere is increasing evidence that inflammation may be a key factor in the development of depression. Cytokines, in particular, have been implicated in the evolution of depression. According to an article published in the August 6, 2014 issue of the Journal of the American Medical Association, studies have shown that depressed patients, irrespective of their physical health, had increased levels of inflammatory markers in their blood and cerebrospinal fluid. These markers include interleukin-6, tumor necrosis factor, and c-reactive protein. The article also states that there is a correlation between inflammation and treatment resistant depression, which accounts for one-third of all depressed patients. Research data shows that inflammatory agents impair the action of traditional anti-depressant medications.

The results of The Avon Longitudinal Study of Parents and Children, conducted in Avon County, England, were recently published in the August 13, 2014 edition of JAMA Psychiatry. The study concluded that higher levels of interleukin-6 in children are associated with a higher risk of depression and psychosis as adults. One of the authors of this study, Dr. Golam Khandaker, was recently noted in Time Magazine as comparing our immune systems to thermostats. “Most of the time, thermostats are turned low and turned up high when we have an infection, but for some people, the thermostat is always turned up high. For these people, they may be more likely to have chronic syndromes, and be more likely to suffer depression.”

New research on treatment for depression has focused on anti-inflammatory agents. A study conducted by Dr. Andrew Miller and colleagues at the Emory University School of Medicine was published in JAMA Psychiatry in 2013 in which the biologic infliximab, a tumor necrosis factor antagonist, was used to treat 60 adult patients with moderately treatment resistant depression. Although infliximab did not prove to be more effective than placebo in treating the depression, the authors found, after categorizing patients on the basis of inflammatory markers, those patients with high baseline C reactive protein had the best response to infliximab. Miller concluded that a biomarker of inflammation like CRP may predict which patients will respond to immunotherapy in depression.

The implications of Miller’s study may also have bearing in finding treatments for other inflammatory diseases often found in patients with depression, such as heart disease, diabetes and cancer. Further studies need to be done, but this is an exciting trend in research of psychiatric disorders. Until an effective anti-inflammatory treatment is found, health guru Dr. Andrew Weil is a very strong proponent of an anti-inflammatory diet in patients with depression, that is, a diet low in processed foods, with an abundance of organic fruits and vegetables, whole grains, fish high in omega-3 fatty acids like salmon, and antioxidant supplementation.

Neuroscience, 2013 Aug 29; 246: 199-229

Dialogues Clin Neurosci 2011; 13(1): 41-53
JAMA 2014 Aug 6; 312: 474-476

By Alexis Gopal M.D.

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