Gothenburg, Sweden—Nearly all drugs approved for treatment of irritable bowel syndrome (IBS) are targeted at intestinal function, but that might not be adequate, according to a new study.

A report in the journal Gastroenterology points out that the brain plays a key role in IBS, which suggests that therapy to improve both bowel function and brain signaling to the gut might better alleviate symptoms.

Diagnostic criteria for IBS, which could affect more than 25 million people in the United States, include abdominal pain, constipation or diarrhea, and irregular bowel activity over a long period.

Researchers from the Sahlgrenska Academy at the University of Gothenburg note that underlying causes are not entirely known but suggest that abnormalities both locally in the intestines and in the central nervous system could be implicated.

“There are studies showing that hypnosis, cognitive behavioral therapy (CBT) and antidepressants can all have an effect against IBS,” explained lead researcher Magnus Simren, MD, PhD. “The view of the gut and brain working together in IBS is beginning to be increasingly accepted, so many gastroenterology clinics are striving to work holistically, in multiprofessional teams, to manage their IBS patients.”

The study team performed a retrospective analysis of data from three cohorts of patients with IBS, based on Rome II or Rome III criteria, seen at a specialized unit for functional gastrointestinal disorders in Sweden from 2002 through 2014. All 407 of the patients—74% female with a mean age of 36 years—underwent assessments of colonic transit time (radiopaque markers); compliance, allodynia, and hyperalgesia (rectal barostat); anxiety and depression (HAD scale), as pathophysiologic factors.

Researchers report that allodynia was observed in 36% of patients, hyperalgesia in 22%, accelerated colonic transit in 18%, delayed transit in 7%, anxiety in 52%, and depression in 24%. Each of these factors was associated with severity of at least one symptom of IBS. Rectal compliance was not associated with more severe symptoms of IBS, however.

Results also showed that at least three pathophysiologic factors were present in 20% of patients, two in 30%, one in 31%, and none in 18%. With increasing number of pathophysiologic abnormalities, there was a gradual increase in IBS symptom severity (P <.0001) and somatic symptom severity (P <.0001), and a gradual reduction in quality of life, according to the report.

“Visceral hypersensitivity, including allodynia and hyperalgesia, abnormal colonic transit, and psychologic factors are all associated with IBS symptoms,” study authors conclude. “These factors have a cumulative effect on gastrointestinal and non-gastrointestinal symptoms, as well as on QOL, in patients with IBS and are therefore relevant treatment targets.”

Study authors emphasize that the patients who had many different abnormalities affecting IBS—in both the gastrointestinal tract and the brain” were also those patients who reported the most severe symptoms and experienced the lowest quality of life.

“In the study, it’s striking how the burden of disease increases successively the more abnormalities the patient has,” Simren said. “This means that we must probably focus the treatment on several of these at the same time to get a better effect. So, this implies that a combination of different treatments tackling factors in the gut and the brain can have a positive effect. But this hypothesis must be investigated in clinical trials first.”

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