DNA, blood pressure. Aneurysm disease runs in families. Some patients have family members who died from aneurysm disease but it was attributed to something else. Investigate your family medical history. The other biggest factor is high blood pressure. Make sure your blood pressure is under control. A final risk factor is smoking. Smoking is bad for many reasons, and it makes aneurysms grow faster.
The Factors. Weakness in the artery wall (usually present since birth), hypertension (high blood pressure, especially poorly-controlled), arteriosclerosis (plaques of cholesterol, platelets, fibrin, and other substance form on the arterial wall), vasculitis (infection in the aorta), Cocaine use (over 40y/o are 4x more likely), marfan syndrome, previous aorta injury, and traumatic injury.