Brain Scans Show Altered Placebo Analgesia Response in IBS
By Anne Harding Reuters Health Information June 03, 2014

NEW YORK (Reuters Health) – Patients with irritable bowel syndrome (IBS) respond differently to placebo analgesia than do healthy controls and ulcerative colitis (UC) patients in remission, according to a new study.

While the healthy controls and the UC patients were able to engage neural downregulation of pain, the IBS patients could not, Dr. Sigrid Elsenbruch of University Hospital Essen in Germany and her colleagues found. And higher levels of depressive symptoms in the IBS patients were linked to a weaker ability to inhibit pain, the team reported in Gut, online May 15.

The findings underscore the importance of patient expectations in treating IBS, Dr. Elsenbruch told Reuters Health. “We need treatments that induce strong positive expectations in these patients, whether the treatment is a placebo or an experimental drug,” she said. A 2008 study found placebo acupuncture effective in IBS, and that stimulated interest in placebo analgesia among gastroenterologists and internists, the researchers note. In the current study, Dr. Elsenbruch and her colleagues sought to compare neural modulation during visceral placebo analgesia in IBS and UC.

To investigate, they performed painful rectal distensions in 17 volunteers with IBS, 15 with UC, and 17 healthy controls matched by age and sex. Using magnetic resonance imaging (MRI), the researchers observed brain activation during the painful stimulus in a placebo condition, in which patients were told they were receiving a potent analgesic; and a control condition, in which patients were told they were receiving an inactive treatment. (Under both conditions, patients received an injection of saline solution through an intravenous drip.)

Both the healthy controls and the UC patients showed reduced activation in brain areas related to pain during placebo analgesia, but the IBS patients did not. The researchers also found a correlation between higher depression scores among the IBS patients and a weaker response to placebo analgesia.

Clinicians treating IBS should find out if a patient is anxious or depressed, and if so, recommend treatment , according to Dr. Elsenbruch, who noted that access to mental health care can vary sharply from country to country.

In addition to improving negative mood, finding ways to help IBS patients feel more in control of their symptoms, for example using relaxation techniques and distraction techniques to cope with pain, can also be helpful, the researcher added.

“If they can do something to help themselves, together of course with their doctor, than that will also raise hopeful expectations toward their pain and being able to manage their pain on a daily basis even when their doctor isn’t around,” she said.

Dr. Elsenbruch and her colleagues are now investigating the role of negative expectations in pain response, with the goal of learning “how we can maximize the good expectations and minimize the bad experiences and bad expectations to really benefit the patient and come up with new behavioral treatments.”

Dr. Paul Enck, a psychologist at University Hospital Tubingen in Germany who was not involved in the research, noted that drug trials have found a stronger placebo response in IBS patients than in UC patients. This could be because the pain stimulus the researchers used in the current study is different from the pain patients with IBS experience from their condition, he added.

Dr. Enck questioned the researchers’ focus on brain imaging data, rather than on patients’ pain ratings. “What is more important is whether the patient says ‘it hurts,'” he said. “We tend to believe brain imaging more than reports from patients. I think this is unfair.”

SOURCE: http://bit.ly/1tAKcj5

Gut 2014.