To understand what causes irritable bowel syndrome, the answers vary among distinct groups of patients. For some, it may be early trauma.
More than 10 percent of the population live with irritable bowel syndrome (IBS), which can cause constipation, diarrhea, or an alternating pattern, combined with bloating, gas, or cramps. About half of them have other chronic illnesses: anxiety, depression, fibromyalgia, chronic fatigue, and pelvic pain are the best documented. This suggests that something going on in the large intestine, also called the gut, is affecting more than bowel movements.
What causes irritable bowel syndrome?
We know that the brain influences the balance of microbes in the gut — and chemicals in the gut affect brain structure. Researchers have found those effects both in mice and in humans.
There’s evidence that IBS patients are more likely than the general population to have suffered trauma in childhood, and that early trauma is linked to lasting changes in the brain and the gut.
A team at the University of California in Los Angeles (UCLA) set out to connect these dots. The gut microbes of some people with IBS look normal. But the team concluded that a subgroup of IBS patients — those with an abnormal pattern of microbes in the gut — have had more history of childhood trauma. Their irritable bowel syndrome symptoms seemed to have lasted longer as well, compared to patients with normal microbe balance.
As the researchers were looking for clues to what causes irritable bowel syndrome, they explored how the illness may play out in the body. They were able to zero in on links between gut microbes and the brain regions involved in handling sensory information — which seem to go astray in people with IBS and otherwise hard-to-explain pain such as fibromyalgia.
March 25, 2020
Christopher Nystuen, MD, MBA