Weakened Immunity Disrupts Mood

Infections and immune disorders linked to increased risk of mood disorders

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Bodies in top-notch shape internally tend to defend themselves against infection and a variety of disease. When those inner defenses are down, however, body and mind alike can suffer.

The risk for mood disorders like major depression and bipolar disorder rises substantially after hospitalizations for autoimmune disease and infection, a new study has concluded.

"Ask your doctor about staying mentally well during illness."

The study’s main author was Michael E. Benros, MD, a psychiatrist with the National Center for Register-based Research at Aarhus University in Central Jutland, Aarhus, Denmark.

The study investigated 33 years’ worth of hospital records from roughly 3.5 million people ranging in age from 15 to 65, researchers wrote. The study period ended in December 2010.

Of the 3.5 million, 91,637 individuals were diagnosed with mood disorder at some point in their life.

Of these patients, over 29,000 were diagnosed as having one or more infection, over 4,000 were diagnosed as having one or more autoimmune disease, and over 2,000 were diagnosed as having an autoimmune disease and an infection.

Having been hospitalized for causes related to autoimmune disease raised study participants risk for eventually being diagnosed with mood disorder by 45 percent, researchers wrote.

Having been hospitalized for an infection raised the mood disorder diagnosis risk by 62 percent, researchers wrote.

When a single hospitalization was for treatment of autoimmune disease and infection at the same time, the risk for developing mood disorder more than doubled, researchers found.

“This landmark study by Benros and his co-workers is the first to use population data from millions of people to track the association between autoimmune disorders, infections and depression,” said Jesse Wright, MD, director of the University of Louisville’s Depression Center, who reviewed the study.

Wright continued: “The substantial increase in risk for depression in people who experienced an autoimmune disorder or infection supports the intriguing theory that immunological changes can be a path to depression.  The findings of this study should prompt researchers to intensify the search for immunological links that could improve the understanding of depression and lead to new treatments.”

According to the researchers, certain sub-groups of patients with autoimmune diseases and infections suffer “sickness behavior.”

That behavior is marked by “...symptoms of fatigue, reduced appetite, apathy, decreased social interaction, impaired concentration and sleep disturbances,” researchers wrote. “Many of these symptoms are similar to symptoms of depression, and studies have suggested that, in vulnerable individuals, prolonged sickness behavior can progress to depression.”

The autoimmune illnesses that the millions of studied patients had included scleroderma, vitiligo, diabetes, celiac disease, multiple sclerosis, autoimmune hepatitis, autoimmune thyroiditis, lupus, Graves’ disease and others. Persons with the human immunodeficiency virus (HIV), another autoimmune disease, were not part of the study.

The infections included ones involving sepsis, hepatitis, the gastrointestinal area, skin, pregnancy, the respiratory system, urogenitals, central nervous system and other parts of the body.

Also, each additional hospitalization for treatment of infections raised the risk for mood disorder even higher, researchers wrote. That risk almost quadrupled, for example, when a patient was hospitalized eight or more times with an infection.

Study participants were listed in both the Danish Psychiatric Central Research Register and Danish National Hospital Registry.

The study was published June 12 in the Journal of the American Medical Association Psychiatry.

Two of six researchers working with Benros reported being paid speaker fees or having their travel expenses covered by pharmaceutical companies.

Reviewed by: 
Review Date: 
June 10, 2013
Last Updated:
August 8, 2013