Irritable Bowel Syndrome Linked to Abnormal Brain Activity
Irritable bowel syndrome (IBS) affects 10 to 15 percent of the U.S. population, predominately women, and can produce severe abdominal pain, bloating, and changes in bowel habits. No physical abnormalities can be identified on examination, and patients are often left with suboptimal symptomatic treatments and the idea that the pain is “all in your head.”
Well, maybe it is.
A new study used magnetic resonance imaging (MRI) to detect differences in brain activity in IBS patients compared to healthy ones. When predictable, mild abdominal pain was stimulated in healthy women, MRI showed decreased activity in the insula, amygdala and brainstem, areas associated with emotion and pain. IBS patients did not show decreased activity in these areas, suggesting they are hard-wired to respond more strongly to pain than others.
The idea that the errors in the perception of pain are the underlying cause of IBS has been around a long time, but this is one of the first studies to demonstrated altered brain activity in the disease. Researchers hope that this information may lead to medications targeted at the brain centers or peripheral nerves responsible for the abnormal signaling.
Patients with IBS often feel left out in the cold. Current treatments for the symptoms of IBS only work temporarily and only in some patients. Many studies have demonstrated a link between anxiety, depression and IBS. Perhaps the link lies in an incorrect, hyperactive perception of pain and danger resulting in increased sensitivity to both emotional and physical pain.
I myself have a long history of abdominal pain that fails to respond to most treatments. I’ve undergone a battery of medical tests, all with no definitive results. IBS is a diagnosis of exclusion, given when all other ausative factors are eliminated as possibilities, so I know that my pain could easily be diagnosed as IBS. And yes, the pain is more frequent and more severe when I am anxious and stressed out, as it is for many women. But that doesn’t mean the pain isn’t real, and that doesn’t mean there isn’t a real organic cause. Even if I don’t have a tumor, or an ulcer, or something else in my belly causing me pain, maybe I just have I hyperactive amygdala, and maybe future researchers will learn how we can retrain or medicate the parts of our brain that are responsible for emotional responses to pain.
Berman S, Naliboff B et al. Reduced Brainstem Inhibition during Anticipated Pelvic Visceral Pain Correlates with Enhanced Brain Response to the Visceral Stimulus in Women with Irritable Bowel Syndrome. J. Neurosci. 2008 28: 349-359.