Stronger coordination between the brain and the stomach's natural rhythm is linked to higher levels of anxiety, depression, and stress, according to the largest study of its kind from Aarhus University.
While most gut–brain research has focused on the lower intestine and gut bacteria, the team of researchers turned to the stomach – the body's upper digestive hub with its own network of nerves.
Scanning more than 240 participants, they found that when brain activity is more tightly synchronized with the stomach's slow electrical waves, people are more likely to report mental distress.
"The stomach's connection to the brain may actually be too strong in people under psychological strain," says postdoc Leah Banellis from the Department of Clinical Medicine, lead author of the study.
A surprising pattern
The stomach has its own nervous system, often called the 'second brain'. Its slow waves occur roughly every 20 seconds, even when we're not eating – a constant background rhythm like the heartbeat.
By combining functional MRI scans with electrogastrography, the researchers measured how closely brain activity matched these waves in each participant.
"Intuitively, we assume stronger body–brain communication is a sign of health. But here, unusually strong stomach–brain coupling seems linked to greater psychological burden – perhaps a system under strain," says Professor Micah Allen, senior author.
A new frontier in mental health research
The enteric nervous system is one of the most complex and independent parts of the peripheral nervous system. Yet little research has focused on the stomach's role in mental health, despite its direct lines of communication with the brain via the vagus nerve.
"This part of the gut has been largely ignored. Most research focuses on the microbiome and lower digestive system. Our results suggest stomach rhythms are also deeply tied to emotional well-being," says Leah Banellis.
The findings are correlational – they do not show that stomach activity causes mental illness. But the researchers believe the pattern could point to a new physiological marker of mental health that is objective, measurable, and grounded in the body's rhythms.
Implications for treatment
If stomach–brain synchronization proves to be a stable feature of mental health, it could open new diagnostic or therapeutic possibilities.
"We know certain medications and even the foods we eat can influence gastric rhythms. One day, this research might help us tailor treatments based on how a patient's body and brain interact – not just what they report feeling," says Micah Allen.
The team now plans follow-up studies with clinical populations to test whether stomach–brain coupling can predict treatment response or signal an upcoming mental health crisis.
"We are just beginning to understand how the body's internal rhythms shape our mental lives. This is one small step toward bridging that gap," says Leah Banellis.
About the study
Study type: Cross-sectional human neuroimaging study using fMRI and electrogastrography
External funding: The Lundbeck Foundation
Conflicts of interest: None declared
Link to scientific publication: https://www.nature.com/articles/s44220-025-00468-6
