Aneurysms are abnormal bulges in the wall of blood vessels that can rupture and cause serious complications. They can occur in many areas of the body, including several parts of the aorta, the blood vessels that supply the brain, and blood vessels in the neck, groin, or legs.Aneurysms often do not have symptoms, so understanding the causes can allow a person to seek medical attention if they are at risk.

High Blood Pressure

Long-term high blood pressure or hypertension can indirectly contribute to or directly cause aneurysms. In more direct cases, high blood pressure weakens the walls of the blood vessels. Research also shows that it may activate systems that then trigger inflammation, further damaging those walls. Abdominal aortic aneurysms have the clearest connections to high blood pressure.

Atherosclerosis

Hardening of the arteries, known medically as atherosclerosis, occurs when fat and other substances accumulate on the lining of blood vessels. This makes them less flexible and causes an increase in pressure. Over time, this can cause the blood vessels to weaken and bulge, eventually leading to an aneurysm.

Blood Vessel Issues

Many other blood vessel issues increase the risk of developing aneurysms. Giant cell arteritis is a disease that triggers inflammation of arteries in the head and neck, which sometimes leads to abdominal aortic aneurysms.Cystic medial necrosis, also known as familial thoracic aortic aneurysm, involves the breakdown of collagen, elastin, and smooth muscle that weakens the arterial wall. Additionally, some people are born with unique arterial features which may increase the risk of an aneurysm.

Infection

Several different infections can potentially result in an aneurysm. Advanced syphilis sometimes leads to inflammation of the aorta — syphilitic aortitis — which then causes an aortic aneurysm. Tuberculosis has links to a pulmonary artery aneurysm called Rasmussen’s aneurysm. Brain infections can cause infectious intracranial aneurysms.

Trauma

Physical trauma can produce aneurysms, though it is rarer than other causes. Falls and motor vehicle crashes are among the more common events that lead to aneurysms.Most people associate physical trauma with cerebral aneurysms, but it can cause others, as well. Sometimes, an injury tears an inner layer of a blood vessel, creating a pseudoaneurysm.

Connective Tissue Disorders

Diseases that affect the body’s connective tissue often result in aneurysms. This includes conditions like autosomal dominant polycystic kidney disease or Loeys-Dietz syndrome, Marfan syndrome, and Ehlers-Danlos syndrome.These disorders make the connective tissues much more fragile, increasing the risk of many types of aneurysms. For many connective tissue disorders, aneurysms are major diagnostic criteria.

Genetics

Genetic influences have a significant effect on a person’s risk for aneurysms. For example, male siblings of people who have experienced aneurysms are four to six times more likely to have an abdominal aortic aneurysm than a person without a family history of aneurysms. As research continues, experts are continually identifying new genetic variations with links to aneurysms.

Obesity

Though not a direct cause, obesity is a major risk factor for aneurysms. Notably, overweight people are more likely to develop conditions like hypertension, high cholesterol, and atherosclerosis, which can lead to aneurysms. Additionally, modern research has found links between obesity-related issues like diabetes and aneurysms.Being overweight can also affect a person’s immune system, increasing the possibility of an aneurysm-causing infection.

Alcohol

Long-term and frequent alcohol consumption can lead to a significant amount of inflammation, which is a major contributor to aneurysms. Research also shows that greater alcohol use may make it far more likely that an aneurysm will rupture. However, former alcohol use did not affect aneurysms once a person abstained from drinking. Researchers advise that people with unruptured aneurysms should stop drinking alcohol immediately.

Smoking

One of the biggest risk factors for aneurysms is smoking. More than 90% of people with abdominal aortic aneurysms smoked at some point in their lives. Smoking weakens the walls of blood vessels, increasing the risk of both aneurysms and ruptures. Some research indicates that it is the duration of smoking, rather than the intensity, that determines the risk.