Depression and Autoimmunity: The Biological Connection

Comorbid depression is common with chronic inflammatory illnesses such as rheumatoid arthritis and psoriasis. The cycle of symptoms even appears to track simultaneously: For instance, it has been known for some time that depression accompanies psoriasis flares, and resolves when the flares subside.

New research suggests that this depression is no mere reactive consequence of the "frustration and discouragement associated with the illness," as Andrew J. Cutler MD puts it in this recorded interview. It is a "true, underlying biological process" recognizable by measuring mediators of inflammation.

Here Dr. Cutler sheds light on the relationship between neurotransmitters, mediators of inflammation, depression, and chronic disease. He is board certified in internal medicine and psychiatry. Dr. Cutler is on the clinical faculty in the Department of Psychiatry at the University of Florida. He is also CEO and Chief Medical Officer of the Florida Clinical Research Center in Bradenton.

Managing Physical Illness and Depression

Key quotes:

•   Depression is not only an illness that is seen by psychiatrists. All physicians need to be aware of this, especially as we learn more about the common underlying biologies and the relationships between some very common illnesses and depression.

•  People who have chronic medical conditions such as ... rheumatoid arthritis or autoimmune conditions ... are at risk for depression. What's been under-appreciated is that this is not just a reactive depression ... We now know that the same biologic conditions that are causing the primary condition ... can cause changes in the brain that induce depression.

•   The brain is loaded with hormone receptors and also cytokine receptors, and we know that some of these inflammatory cytokines have a negative effect on the brain's ability to make ... the neurotransmitters serotonin, norepinephrine, and dopamine. ... involved with the pathogenesis of depression. We also know that inflammation can prevent neurogenesis and be toxic to nerve cells.

•   Charles Raison ... treated a group of patients with depression with infliximab. ... He found that overall the drug did not beat placebo at treating depression. However, he found that when markers for inflammation were elevated, those patients did respond and the depression got better. This is the first time we have a biologic treatment rather than the standard antidepressants. .

REFERENCE:

Raison CL, Rutherford RE, Woolwine BJ et al. A Randomized Controlled Trial of the Tumor Necrosis Factor Antagonist Infliximab for Treatment-Resistant Depression:  The Role of Baseline Inflammatory Biomarkers. JAMA Psychiatry (2013) 70:31-41