New study shows bidirectional link between inflammatory bowel disease and depression

Summary:A new study shows that patients diagnosed with IBD were nine times as likely to develop depression than the general population. In addition, their siblings who did not suffer from IBD were almost two times as likely to develop depression. Conversely, 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.

Source:University of Southern California – Health Sciences

Inflammatory bowel disease (IBD) is a chronic condition involving inflammation of the digestive tract, affecting some 1.6 million Americans. Depression affects more than 16 million Americans.

A new study from Keck Medicine of USC shows that patients diagnosed with IBD were nine times as likely to develop depression than the general population. In addition, their siblings who did not suffer from IBD were almost two times as likely to develop depression.

Conversely, 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.

Zhang and his fellow researchers analyzed the data of more than 20 million people from Taiwan’s National Health Insurance Research Database, which contains comprehensive medical information on more than 99% of Taiwanese residents.

For 11 years, they tracked patients with either IBD or depression and their siblings without either condition, comparing onset of depression or IBD with a control group of people without either condition, but with similar age, sex and socioeconomic status.

Zhang hypothesizes that many factors may contribute to the bidirectional nature of the disorders, including environmental stressors, the gut microbiome (consisting of bacteria, fungi and viruses) 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.”

What surprised researchers was 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.

The researchers are not sure why siblings of patients with depression are more likely to be diagnosed with IBD. Zhang surmises that there may be a shared genetic susceptibility for either disease that presents differently in family members.

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.

Through more research and better understanding of the gut-brain axis, he envisions leveraging the newfound connection between the conditions to improve the prevention, diagnosis and treatment of IBD and mental disorders.

The study was supported by grants from the Taipei Veterans General Hospital and the Ministry of Science and Technology, Taiwan.

Abstract

Bidirectinal association between inflammatory bowel disease and depression among patients and their unaffected siblings

Background and Aim

Approximately 30% of inflammatory bowel disease (IBD) patients develop depression. Conversely, several studies reported increased IBD risk among patients with depression. Such bidirectional relationship has not been reported within one representative cohort, nor investigated among patients’ family members. These associations may further implicate the gut–brain axis in IBD.

Methods

We conducted parallel retrospective cohort analyses to investigate depression risk among IBD patients and their unaffected siblings, and IBD risk among patients with depression and their unaffected siblings using the Taiwanese National Health Insurance Research Database. Individuals were followed up to 11 years for new-onset depression or IBD. Controls were matched to unaffected siblings based on predefined characteristics.

Results

To investigate depression risk among IBD – 422 IBD patients, 537 unaffected siblings, and 2148 controls were enrolled. During follow-up, 78 (18.5%) IBD patients, 26 (4.8%) unaffected siblings, and 54 (2.5%) controls developed depression. Adjusted odds ratios (ORs) for depression among IBD patients and unaffected siblings were 9.43 (95% CI 6.43–13.81; P < 0.001) and 1.82 (95% CI 1.14–2.91; P = 0.013), respectively. To investigate IBD risk among depression – 25 552 patients with depression, 26 147 unaffected siblings, and 104 588 controls were enrolled. During follow-up, 18 (0.70/1000) depression patients, 25 (0.96/1000) unaffected siblings, and 58 (0.55/1000) controls developed IBD. ORs for IBD among depression patients and unaffected siblings were 1.87 (95% CI 1.07–3.26; P = 0.028) and 1.69 (95% CI 1.05–2.69; P = 0.029), respectively.

Conclusions

This population-based study elucidates bidirectional association between IBD and depression. Elevated risks for either disease among patients and their unaffected siblings suggest shared etiologic contributors, offering novel insight into the gut–brain axis’ influence in IBD pathophysiology.