Irritable bowel syndrome is not a disease. It is a functional disorder, which means that there is a problem in how the muscles in the intestines work. Irritable bowel syndrome is characterized by gas, abdominal pain, and diarrhea or constipation, or both. Although the syndrome can cause considerable pain and discomfort, it does not damage the digestive tract as diseases do. Also, irritable bowel syndrome does not lead to more serious digestive diseases later.
Diverticulosis is an uncommon and serious problem.
Actually, the majority of Americans over age 60 have diverticulosis, but only a small percentage have symptoms or complications. Diverticulosis is a condition in which little sacs or out-pouchings called diverticula, develop in the wall of the colon. These tend to appear and increase in number with age. Most people do not have symptoms and would not know that they had diverticula unless x-ray or intestinal examination were done. Inflammatory bowel disease is caused by psychological problems.