Mental health answers are hiding inside stomach? Nearly 7 in 10 psychiatric patients found to have same surprising pattern

The connection between mental health and physical health may run deeper than previously thought, with growing research pointing towards the gut as an important part of the brain's wider network. Now, a large study has found a striking pattern among people with psychiatric disorders, raising fresh questions about how closely digestive and mental health may be linked.

Researchers analysing health records of nearly 700,000 adults in South Korea found that chronic gastrointestinal (GI) disorders were far more common among people with psychiatric conditions than among those without such diagnoses. Nearly seven in 10 psychiatric patients in the study had a chronic GI disorder, compared with just over half of the matched control group.

What the South Korean study found

The study, published in the Journal of Psychosomatic Research, used data from South Korea's National Health Insurance Service. They studied adults 18 or older with at least one psychiatric diagnosis from 2021 to 2022.


The initial analysis included 526,918 adults with psychiatric disorders and 473,082 people without psychiatric diagnoses. After propensity score matching, researchers compared 348,304 people in each group, resulting in a final cohort of 696,608 individuals.

Among those with psychiatric disorders, 69.8% had a chronic GI disorder. The figure was 52.1% among the matched control group.

Overall, people with psychiatric disorders had significantly higher odds of having chronic GI disease.

Functional GI disorders showed strongest association

The researchers divided gastrointestinal diseases into three broad categories: functional GI disorders, organic GI disorders and hepatobiliary-pancreatic diseases.

The strongest association was seen with functional GI disorders. There were also higher odds for organic GI disorders and hepatobiliary-pancreatic diseases, although the associations were not as strong as those seen with functional conditions.

The findings are important since functional gastrointestinal disorders can present with symptoms in the absence of structural abnormalities typically seen in some organic diseases.

The stronger link between psychiatric disorders and functional GI conditions supports the clinical importance of the gut-brain axis, said the researchers.

However, the study does not establish that psychiatric disorders cause gastrointestinal disease, or that GI disorders directly cause mental health conditions. It shows that the two occur together at a substantially higher rate.

Anxiety and depression have long been linked to gut problems

The connection is not entirely new. Earlier research has also found higher levels of psychological disorders among people with gastrointestinal conditions.

A review of studies involving irritable bowel syndrome (IBS) and ulcerative colitis found that both groups had higher prevalence and severity of depression and anxiety compared with healthy controls.

The review, published in Psychological Medicine, found excess depression and anxiety among patients with both conditions. The authors note that the relationship may possibly go in more than one direction, with chronic gastrointestinal illness affecting psychological well-being.

Gut microbes may be part of the link

Studies of functional gastrointestinal disorders have increasingly targeted the microbiome-gut-brain axis. This refers to the two-way communication between the digestive system and the brain, with the gut microbiome also playing a role in this interaction.

The gut microbiome was described as a key component of this two-way mechanism in the review on functional gastrointestinal disorders and psychiatric symptoms.

The South Korean study's findings add large-scale population evidence to this area of research, particularly because the association was stronger for functional GI disorders than for organic diseases.

Mental health risks may appear before IBD diagnosis

Another nationwide study, reported by EurekAlert, found that the relationship can also be seen around inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis.

Researchers studied more than 40,000 Swedish IBD patients between 2007 and 2023, comparing them with nearly 180,000 people from the general population and about 26,000 IBD-free full siblings.

The risk of psychiatric disorders began increasing two to three years before an IBD diagnosis, peaked during the first six months after diagnosis and remained elevated for years.

The increase was mainly driven by major depressive disorder, anxiety disorders and substance misuse.

Lead author Jiangwei Sun, PhD, said, “It is time to actively manage psychiatric conditions in patients with IBD.”