Fear strongly influences pain perception in inflammatory bowel disease patients

Pain perception in affected individuals is more strongly influenced by learned fear than in healthy individuals. Changes along the gut-brain axis related to chronic inflammation may explain this.

Many patients with inflammatory bowel disease (IBD) suffer from abdominal pain even between acute inflammatory flare-ups. Altered processing of pain in response to fear may be involved. This is the conclusion of a research team at Ruhr University Bochum, Germany, involving Dr. Hanna öhlmann. The researchers compared the perception of pain in healthy individuals and patients with IBD using a learning experiment. Based on their findings, they recommend the development of personalized treatments that take such psychological mechanisms into account. The study was published in the scientific magazine PAIN on November 26, 2025.

The relationship between fear and pain

The fact that patients with inflammatory bowel disease (IBD) often experience symptoms like abdominal pain even during phases of disease remission suggests that mechanisms other than acute inflammatory processes contribute to the persistence of pain. One possibility is that the emotional processing of pain is altered."

Dr. Hanna öhlmann, Center of Medical Psychology and Translational Neuroscience, Ruhr University Bochum

A critical emotion in the context of pain is fear. Abdominal pain signals potential tissue damage or upcoming gastrointestinal symptoms, which is why we quickly learn when events or stimuli occur in close temporal proximity to abdominal pain. We then start to fear and avoid these stimuli - a response that normally protects us. However, studies in other chronic pain conditions, such as irritable bowel syndrome, show that affected individuals tend to acquire pain-related fear more strongly than healthy individuals. "Together with persistent avoidance behavior, this can cause abdominal pain to be perceived as increasingly threatening, which in turn can perpetuate the pain," says öhlmann.

Learning to fear pain

To investigate whether this is also true for IBD patients, the researchers recruited 43 participants for their experimental study. 21 of these participants had been diagnosed with ulcerative colitis, a subtype of IBD that primarily affects the colon. The remaining participants were healthy controls.

On the first study day, participants were shown various symbols on a screen. One symbol was repeatedly paired with painful heat applied to the lower abdomen, while another symbol was never paired with pain. In this way, the participants acquired pain-related fear. This was followed by an extinction phase during which all symbols were shown without any painful stimulation, causing a decrease in pain-related fear again.

On the second study day, the extinction phase was repeated. Then, participants were unexpectedly exposed to painful heat again without any visual cues. "We wanted to test whether IBD patients perceive the pain differently than healthy individuals, and whether this is linked to the strength of fear learning," explains öhlmann.

Patients perceive pain as more unpleasant and intense

The results show that IBD patients perceived the pain as more unpleasant and more intense upon re-exposure compared to healthy participants. More pain-related fear acquired on the first study day was associated with a more unpleasant and intense pain perception on the second study day - but only in the patient group. Further analyses revealed that fear-learning primarily shaped the perceived unpleasantness of the pain and only indirectly affected pain intensity. The emotional component of pain thus played an important role.

"Interestingly, IBD patients did not acquire more pain-related fear on the first study day than the healthy participants," notes öhlmann. "So it wasn't the learning process itself that differed, but rather how the fear was linked to pain perception." This suggests that the recurring, strong inflammatory flare-ups may, over time, alter how pain is centrally processed in relation to fear. Pain may then be experienced more intensely even if the fear itself is not excessively strong. This idea is further supported by previous studies, which show structural and functional brain changes in patients with IBD, particularly in brain regions involved in processing fear and pain.

Implications for treatment

Treatment for IBD has so far mainly focused on controlling inflammation in the gastrointestinal tract. However, psychological factors – such as stress, persistent avoidance, or pain-related fear – could also play a crucial role. “This is why chronic abdominal pain should be recognized as an important characteristic of the disease and treated accordingly,” says Öhlmann. “Patients who continue to experience abdominal pain despite successfully controlled inflammation may particularly benefit from a more holistic perspective. Our data suggest that psychological approaches – for example from cognitive behavioral therapy, which specifically address fear and avoidance – should be systematically investigated, including in other chronic inflammatory diseases associated with pain, such as rheumatoid arthritis or endometriosis.”