Inflammatory bowel disease (IBD) affects some 1.6 million Americans. Approximately 30% of these patients develop depression. Is there a link between the 2 conditions?

A new study from Keck Medicine of USC shows that patients diagnosed with IBD were 9 times as likely to develop depression then the general population. In addition, their siblings who did not suffer from IBD were almost twice as likely to develop depression. When the data were analyzed from a different perspective, the researchers found that patients with depression were two times as likely to develop IBD, and their siblings without depression were more than one and a half times as likely to develop IBD.

 “This research reveals a clinical overlap between both conditions and is the first study to investigate the two-way association between IBD and depression in siblings,” said Bing Zhang, MD, a gastroenterologist with Keck Medicine and co-lead author of the study.

The physiologic links between these conditions are yet unclear. Many factors may contribute to the bidirectional nature of the disorders, including environmental stressors, the gut microbiome, and genetics.

“The finding that people with IBD are more prone to depression makes sense because IBD causes constant gastrointestinal symptoms that can be very disruptive to a patient’s life,” he said. “And the elevated depression risk among siblings of IBD patients may reflect caregiver fatigue if the siblings have a role in caring for the patient.”

Researchers were surprised that patients with depression were prone to IBD. Zhang speculates that this discovery may have to do with what is known as the gut-brain axis, a scientifically established connection between the gastrointestinal system and the central nervous system, which consists of the spinal cord and the brain. For example, he said, inflammation of the brain, which plays a role in depression, may be linked to the inflammation of the gastrointestinal tract, a hallmark of IBD.

Zhang hopes that the study findings will encourage health care professionals to take both family history and the relationship between gastrointestinal and mood disorders into consideration when evaluating or treating patients with either IBD or depression.

The full study may be read here.

 Photo from Pixabay.