Nearly half of depression risk factors overlap with physical illnesses, especially gut disease

Original paper: https://www.nature.com/articles/s41588-026-02735-3

https://medicalxpress.com/news/2026-09-depression-factors-overlap-physical-illnesses.html

QIMR Berghofer researchers have identified a strong genetic link between gut-related health conditions and depression in a study offering new insights into why physical illnesses often accompany the mental health condition.

Physical illnesses can contribute substantially to poor health outcomes in people with depression, who die up to 12 years earlier than those without the condition.

In an effort to better understand why, the QIMR Berghofer study looked at the genetic relationship between major depressive disorder and four groups of physical diseases: cardiovascular, metabolic, gastrointestinal and immune disorders.

While all four were genetically linked to depression, gastrointestinal diseases such as irritable bowel syndrome, gastroesophageal reflux disease, gallstone disease and peptic ulcer disease showed the strongest association.

The study, which was published in Nature Genetics, found that the genetic risk factors linked to these physical illnesses overlapped with almost half of those involved in depression.

Lead author and doctoral student Damian Woodward said the findings highlight the importance of looking beyond the brain when treating depression.

"We found gastrointestinal diseases had the strongest shared genetic relationship with depression, confirming that the gut-brain axis plays a key role in why depression commonly occurs alongside physical illness," Woodward said.

"The gut is often referred to as the second brain, sharing many of the same signaling chemicals and containing a high number of nerve cells. There is constant communication between the gut and brain, and we identified genetic roots affecting this communication that contribute to depression, gut dysfunction and other conditions such as immune-related diseases."

Professor Eske Derks, head of QIMR Berghofer's Translational Neurogenomics Laboratory, said the findings could help improve outcomes for people living with depression and other health conditions.

"People with depression often experience a range of serious physical illnesses. By better understanding the biological pathways linking these conditions, we hope to identify new treatment opportunities and help reduce the heavy health burden associated with depression," Derks said.

In addition to raising clinical awareness of conditions shared by people with depression, researchers also hope to identify new treatment options, including repurposing existing medications.