Patients with IBS experience a loss of appetite, abdominal distention (a swollen abdomen) and abdominal fullness. Emotional distress and depression can occur. IBS patients can also have chronic and frequent diarrhea or chronic and frequent constipation, which may occur along with pain. Other symptoms of IBS include abdominal pain, which comes and goes, occurs after meals and reduces after a bowel movement.
The NDDIC notes that doctors have not found a specific cause for IBS, but different theories exist. For example, IBS may have to do with sensitivity of the colon or large intestine. Patients may have IBS if they have a bacterial infection in the gastrointestinal tract or have diminished serotonin receptor activity in the gastrointestinal tract. Another possible cause is that the colons in IBS patients do not have normal motility.
A new study published in the journal Gastroenterology notes that women with IBS can have changes in the brain, specifically in the gray matter. The brain is made up of both gray matter and white matter. The gray matter contains cell bodies, while the white matter contains the nerve fibers.