People with the greatest risk are white men over age 55. Aneurysms are among the top ten causes of death among this group. Brain artery aneurysms affect both men and women at younger ages. Men are three times more likely to have abdominal aortic aneurysms than women. Aneurysms appear to be caused by a congenital weakness in the vessel wall, high blood pressure, arteriosclerosis, injuries, infection, smoking, and other diseases.
Most aortic aneurysms grow slowly.
Over many years, the walls slowly stretch and enlarge like a balloon. The normal aorta is about as wide and as tough as a garden hose. An aneurysm in this blood vessel can grow to the size of an orange before it ruptures. One-third of aneurysms that are larger than 2 inches wide rupture within 5 years. The risk of dying from a ruptured aneurysm is about 90 percent.