First the painful belly cramps, then the mad dash to the bathroom, then the way-too-watery “number two.” Ugh, diarrhea. It’s not only gross and uncomfortable…diarrhea actually can be quite dangerous. That’s why I want to warn you about a startling connection between diarrhea and depression—that’s right, depression.

The virulent bacterial infection Clostridium difficile (C. diff) causes severe stomach cramps and horrible watery or bloody diarrhea. It can inflame and damage the colon, is notoriously hard to treat—and it can be fatal. Risk factors for C. diff include antibiotics, which upset the balance of microorganisms in the gut…and hospitalization, because the bacteria are hard to eradicate and easily passed from one person to another. Those risk factors are well-known. But it’s a surprise that depression—and certain antidepressants, too—are linked to an increased risk for this dreadful disease, according to a new study.

Now, I want to clarify that the research shows only an association—it does not prove that depression or antidepressants can cause C. diff…nor does it prove that C. diff can cause depression (though clearly the infection can interfere with quality of life). Yet given how prevalent depression is (affecting 10% of men and 15% of women at some point in their lives) and how serious both depression and C. diff can be, it’s important to be aware of the link.

DEPRESSION CONNECTION

For the study, researchers first examined Medicare records of nearly 17,000 older Americans to determine which patients were infected with the C. diff bacteria…and which ones had received a diagnosis of depression. They also obtained information about the patients’ marital status and living arrangements.

What they discovered: Of the 404 people in the study group with a confirmed diagnosis of C. diff, more than one-third had been diagnosed with major depression. Crunching the numbers, the researchers found that people with depression had a 36% higher risk for C. diff than those without depression.

Also noteworthy was the fact that older widowed people had a 54% increased risk for C. diff compared with older married people…and that seniors who lived alone had a 33% increased risk compared with those who lived with someone else. Considering how widespread depression is among the elderly—due in part to their social isolation—it’s worrisome to know that there is this added risk for C. diff among a population that is already vulnerable.

ANTIDEPRESSANTS AND DIARRHEA

The second part of the study involved 4,047 hospitalized patients who were being tested for C. diff because they had diarrhea. Their hospital records listed the medications that the patients were taking. Of the 468 people who tested positive for C. diff, 84% were taking antibiotics. This was not surprising, because the link between C. diff and antibiotics is already well-established.

What was surprising—and troubling—was the fact that patients taking certain antidepressants had a much higher chance of having C. diff. Compared with patients who did not take antidepressants…

  • Those taking fluoxetine (Prozac, Sarafem) had double the risk for C. diff.
  • Those taking mirtazapine (Remeron) also had double the risk for C. diff.
  • Those who were taking both trazodone (Desyrel) and mirtazapine had a C. diff risk that was six times higher.

The eight other antidepressants analyzed were not associated with an increased risk of developing C. diff.

THE “BRAIN-GUT AXIS”

Proper bowel function depends on having normal flora, meaning the right balance of the right intestinal bacteria. When people take antibiotics, “friendly” bacteria are eliminated along with harmful bacteria—and the loss of those beneficial bacteria creates an opportunity for C. diff to proliferate in the intestinal tract.

What might explain the link between depression medication and increased risk for C. diff? Researchers suspect that certain antidepressants also might alter a person’s normal flora…and we know that antidepressants can affect the gut, sometimes causing nausea and/or diarrhea.

As for the connection between depression itself and C. diff, researchers suspect that it has do to with the brain-gut axis, meaning the interaction between the brain and the gut. We do know that mice forced into depression by being separated from their mothers developed colitis (inflammation of the intestine). And in humans, the link between depression and inflammatory bowel disease (an umbrella term that includes ulcerative colitis and Crohn’s disease) is well-established, though not well understood. Depression also can affect the appetite, perhaps leading to dietary changes that alter the normal flora…and it may impair immune function.

Bottom line: If you suffer from depression or are taking an antidepressant, talk to your doctor about ways to reduce your risk for C. diff, especially if you are prescribed antibiotics or if you need to be hospitalized for some reason. If you get diarrhea that is severe or that lasts more than two to three days, see a doctor immediately. For additional information on prevention and treatment, check out the box, “More on Clostridium Difficile,” above.