IBD Risk May Be Increased With Depression but Lowered With Antidepressants
By Lorraine L. Janeczko
NEW YORK (Reuters Health) - Depression appears to be linked with an increased risk of developing inflammatory bowel disease (IBD), but antidepressant use might bring that risk back down, researchers in Canada report.
"Individuals who are diagnosed with depression have a higher likelihood of being subsequently diagnosed with IBD. A diagnosis of depression doubled the risk of being diagnosed with both Crohn's disease and ulcerative colitis," said Dr. Gilaad G. Kaplan of the University of Calgary, in Canada.
"We discovered that taking antidepressants protected against the development of IBD," he told Reuters Health by email. "This finding suggests that treating patients with depression may mitigate their subsequent risk of developing IBD."
The findings were published online October 18 in the journal Gut.
Dr. Kaplan and colleagues used The Health Improvement Network (THIN) of anonymized electronic medical records from primary care clinics in the United Kingdom to identify a cohort of patients with new-onset depression between 1986 and 2012.
They identified more than 400,000 patients with incident depression. THIN patients who did not meet criteria for depression were assigned to the referent group.
After controlling for demographic and clinical covariates, individuals with depression were at significantly higher risk of developing Crohn's disease than those in the referent cohort of more than 5 million people (adjusted hazard ratio, 2.11) and ulcerative colitis (aHR, 2.23).
Using selective serotonin-reuptake inhibitors (SSRIs) or tricyclic antidepressants (TCAs) was linked with a lower risk of developing Crohn's disease, while using mirtazapine, serotonin-norepinephrine-reuptake inhibitors (SNRIs), SSRIs, serotonin modulators or TCAs was tied to reduced risk of ulcerative colitis.
"This study highlights the importance of treating depression in order to potentially avoid complications that may occur outside the mind - for example, developing IBD," Dr. Kaplan explained.
Dr. Kaplan encourages healthcare providers to investigate the possibility of IBD in patients with depression and chronic gastrointestinal symptoms such as diarrhea or rectal bleeding.
"How are the mind and the gut connected such that a mental health condition could incite inflammation in the bowel?" Dr. Kaplan wondered. "Understanding the mechanism of this relationship may give us a greater understanding of the root causes of both depression and IBD."
Dr. Faten N. Aberra, an associate professor of medicine at the Hospital of the University of Pennsylvania, told Reuters Health by email, "It is surprising that antidepressants seem to eliminate the risk altogether. It would have been more convincing if the authors presented data on the duration of antidepressant use."
"I am also not sure if using a 6-month window between a depression diagnosis and developing IBD is enough of a gap to be certain that the depression occurred first," she added. "Many patients have symptoms for months or years prior to their diagnosis of IBD but their symptoms may have been unrecognized as a sign of IBD."
Also, noted Dr. Aberra, who also was not involved in the study, "We do not know how long patients were on therapy and if they took therapy as prescribed (a limitation of a population database study)."
Dr. Eva M. Szigethy, a professor of psychiatry, pediatrics and medicine at the University of Pittsburgh in Pennsylvania, said by email, "The increased risk of developing IBD in depressed versus non-depressed adults is not surprising but the findings that antidepressants can be protective is very novel."
"Of course from the study design, we don't know if this protection is just a delay in diagnosis or is actually preventing IBD," Dr. Szigethy, who also was not involved in the study, told Reuters Health. "But either way, it is an actionable finding prompting providers to treat depression with serotonergic antidepressants that have known anti-inflammatory effects."
"As the authors note, the study design's reliance on information extracted from medical records, enables the possibility of false-positive and -negative findings," Dr. Sigethy said. "Further, it is important to note that there is an association but not causal proof that antidepressants are protective against the development of IBD."
The researchers plan to conduct functional MRI brain scans of patients with IBD to investigate possible structural or functional differences in patients with IBD, and whether these differences can explain the connection between depression and IBD.
A Canadian Institutes of Health Research Team Grant in Inflammation in Chronic Disease funded the study.
Dr. Kaplan and coauthors hold a patent involving the treatment of inflammatory and autoimmune conditions, and the researchers has financial relationships with companies making antidepressants.
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