People who are depressed or lonely are at increased risk of Clostridium difficile infection, according to recently published research.

University of Michigan Health System researchers conducted two studies. In one, they interviewed nearly 16,800 participants every other year from 1992-2006. The average age of participants was 68. The researchers linked the interview information with data from Centers for Medicare & Medicaid Services Standard Analytical Files from a variety of healthcare settings, including skilled nursing facilities. The second study focused on C. diff patients in hospitals.

The results of the first study showed a relationship between depression and C. diff infection. Those with major depression were 36% more likely to get C. diff, and those with depressive disorders were 35% more likely to become infected. Widowed participants were 54% more likely to be diagnosed with C. diff, while people who did not live alone were 25% less likely to get the infection.

“Self-reports of feeling sad or having emotional, nervous or psychiatric problems at baseline were also associated with the later development of CDI,” the researchers wrote.

The second study showed that patients on Remeron (mirtazapine) and Prozac (fluoxetine) were twice as likely to be diagnosed with C. diff.

Previous studies have also linked depression and C. diff, the researchers noted. However, it remains unclear whether depression itself spurs microbial changes in the gut that are conducive to C. diff , or whether medications given to treat depression are the culprits.

The research was funded in part by the National Institute on Aging, and by a $7.5 million award from the National Institute of Allergy and Infectious Diseases. It appears in the journal BMC Medicine.

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