Background and objective Approximately 30% of patients with inflammatory bowel disease (IBD) develop depression. In contrast, several studies reported an increased risk of IBD among patients with depression. Such a bidirectional relationship has not been reported within a representative cohort, nor has it been investigated among patients’ relatives. These associations may further implicate the gut-brain axis in IBD. Methods We performed parallel retrospective cohort analyzes to investigate the risk of depression among patients with IBD and their unaffected siblings, and the risk of IBD among patients with depression and their unaffected siblings using the National Health Insurance Research Database. from Taiwan. Individuals were followed for up to 11 years for new-onset depression or IBD. Controls were matched to unaffected siblings based on predefined characteristics. Results To investigate the risk of depression 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. The adjusted odds ratios (ORs) for depression between IBD patients and unaffected siblings were 9.43 (95% CI: 6.43–13.81; P < 0.001) and 1.82 (95% CI: 6.43–13.81; P < 0.001). 95%: 1.14–2.91, P = 0.013), respectively. To investigate the risk of IBD among depression: 25,552 patients with depression, 26,147 unaffected siblings, and 104,588 controls were enrolled. During follow-up, 18 (0.70/1000) patients with depression, 25 (0.96/1000) unaffected siblings, and 58 (0.55/1000) controls developed IBD. The ORs for IBD between patients with depression 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 clarifies the bidirectional association between IBD and depression. Elevated risks of either disease between patients and their unaffected siblings suggest shared etiologic contributors, offering novel insight into the influence of the gut-brain axis on the pathophysiology of IBD. |
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The link also extends to siblings of patients with inflammatory bowel disease or depression
Inflammatory bowel disease (IBD) is a chronic condition involving inflammation of the digestive tract and affects about 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 more likely to develop depression than the general population. Additionally, their siblings who did not have IBD were almost twice as likely to develop depression.
In contrast, patients with depression were twice 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 bidirectional association between IBD and depression in siblings,” said Bing Zhang, MD, a gastroenterologist at Keck Medicine and co-senior author of the study.
Zhang and his fellow researchers analyzed data on more than 20 million people from Taiwan’s National Health Insurance Research Database, which contains complete medical information on more than 99 percent of Taiwanese residents.
For 11 years, they followed patients with IBD or depression and their siblings without either condition, comparing the onset of depression or IBD with a control group of people without either condition, but with age, sex and similar socioeconomic level.
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 detrimental to the patient’s life,” he said. "And the elevated risk of depression among siblings of IBD patients may reflect caregiver fatigue if siblings have a role in caring for the patient."
What surprised the 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, brain inflammation, which plays a role in depression, could be related to inflammation of the gastrointestinal tract, a hallmark of IBD.
Researchers aren’t sure why siblings of patients with depression are more likely to be diagnosed with IBD. Zhang hypothesizes that there may be a shared genetic susceptibility to either disease that presents differently in family members.
Zhang hopes the study’s findings will encourage health professionals to consider both family history and the relationship between gastrointestinal and mood disorders when evaluating or treating patients with IBD or depression.
Through more research and a better understanding of the gut-brain axis, he plans to harness the newly discovered 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 of Taiwan.
