Several groups face elevated aneurysm risk, including men over 65, current smokers, people with high blood pressure, and those with certain genetic conditions. Your specific risk profile depends on the type of aneurysm, since the factors that weaken blood vessels in the abdomen differ somewhat from those affecting the brain.
Aneurysms occur in three main locations: the abdominal aorta (the large vessel supplying blood to your lower body), the thoracic aorta (the portion passing through your chest), and the brain. Each has overlapping but distinct risk patterns worth understanding separately.
Age and Sex: The Biggest Demographic Splits
For abdominal aortic aneurysms (AAA), being male is one of the strongest risk factors. Men develop AAAs at roughly four to five times the rate of women of the same age, and AAA ranks as the 10th leading cause of death in white men between 65 and 74. The peak prevalence in men hits 5.9% between ages 80 and 85. Women aren’t immune, but their aneurysms tend to develop 10 to 15 years later than men’s, with prevalence not reaching comparable levels until after age 90.
Brain aneurysms flip this pattern. Women are about 60% more likely than men to have an intracranial aneurysm overall, and after menopause, the risk roughly doubles compared to men. While the general population carries a 3% to 5% prevalence of brain aneurysms, that figure reaches about 6% in women. The gap widens with age: before 50, women and men are nearly equal, but after 50, the female-to-male ratio climbs to 2.2 to 1. Declining estrogen levels after menopause likely play a role, though researchers believe hemodynamic forces and inflammatory differences between sexes also contribute.
Smoking: The Most Modifiable Risk Factor
Smoking damages blood vessel walls throughout the body, making it a major risk factor for every type of aneurysm. Current smokers are about 2.5 times more likely to experience a brain aneurysm rupture than people who have never smoked. The relationship is dose-dependent at a population level: for every 1 percentage point decrease in a population’s smoking rate, the incidence of aneurysm-related bleeding in the brain drops by 2.4%.
The encouraging finding is that quitting makes a real difference. Studies comparing current smokers to former smokers found that current smokers had a 42% higher rupture risk. And when researchers compared former smokers to people who never smoked, the difference was no longer statistically significant, suggesting that the elevated risk fades meaningfully after quitting. “Former smoker” in these studies generally meant at least one year of cessation.
Smoking history is so central to aortic aneurysm risk that it shapes screening recommendations. The U.S. Preventive Services Task Force recommends a one-time ultrasound screening for men aged 65 to 75 who have ever smoked. For men in the same age range who have never smoked, screening is offered more selectively. For women who have never smoked and have no family history, routine screening is not recommended.
High Blood Pressure and Arterial Damage
Chronic high blood pressure is one of the clearest pathways to aneurysm formation. When blood pressure stays elevated, the entire aorta is exposed to increased wall stress. Over time, this mechanical strain triggers a cascade of changes: the smooth muscle cells in artery walls proliferate and rearrange, organized elastic fibers break down, and collagen deposits accumulate. The result is a stiffer, less resilient vessel that’s more prone to bulging.
High blood pressure also disrupts the inner lining of arteries and damages the tiny blood vessels that supply the artery wall itself, further weakening it from the inside out. Inflammation compounds the problem, with immune signals promoting cell death and scarring within the vessel wall. This is why blood pressure control is consistently emphasized as a way to slow aneurysm growth in people who already have one.
Genetic Conditions That Weaken Blood Vessels
Several inherited connective tissue disorders substantially raise aneurysm risk because they affect the structural proteins that hold blood vessel walls together. The most well-known include:
- Marfan syndrome: Caused by a defect in fibrillin-1, a protein that gives connective tissue its strength. Aortic root aneurysms are a hallmark complication.
- Ehlers-Danlos syndrome (vascular type): Involves defects in collagen production, leading to fragile blood vessels and skin. Arterial rupture can occur even at younger ages.
- Loeys-Dietz syndrome: Affects growth factor signaling in blood vessel walls, causing widespread arterial tortuosity and aneurysm formation throughout the body.
These conditions are relatively rare, but if you’ve been diagnosed with one, vascular monitoring is a routine part of your care.
Polycystic Kidney Disease and Brain Aneurysms
Autosomal dominant polycystic kidney disease (ADPKD) carries a notably higher rate of brain aneurysms. Between 5% and 9% of people with ADPKD develop an intracranial aneurysm, which is three to five times the rate in the general population (2% to 3%). Interestingly, once an aneurysm forms, the rate at which it grows or new ones develop appears similar to the general population. Still, because the baseline frequency is so much higher, people with ADPKD are often screened for brain aneurysms, particularly if they also have a family history of aneurysm or subarachnoid hemorrhage.
Family History as an Independent Risk
Even without a named genetic syndrome, having a first-degree relative (parent or sibling) who had an aneurysm increases your own risk. Family history of brain aneurysm is one of the clearly identified independent risk factors for developing one. This likely reflects shared genetic variants affecting blood vessel structure or inflammatory responses that haven’t been tied to a single condition. If multiple family members have had aneurysms, screening discussions with a specialist are reasonable.
How Size and Location Affect Rupture Risk
Not all aneurysms are equally dangerous. For brain aneurysms, reported critical diameters where rupture risk increases range from 4 to 10 mm, though guidelines have trended toward earlier intervention over time. The International Study of Unintracranial Aneurysms revised its threshold from 9 mm down to 6 mm. Japanese guidelines recommend considering treatment for aneurysms larger than 5 mm. Small aneurysms under 10 mm carry about a 1.3% annual rupture risk, which accumulates meaningfully over years or decades.
Location matters too. Aneurysms in certain parts of the brain’s circulation carry higher rupture risk at smaller sizes, which is why treatment decisions factor in both measurements and position rather than relying on size alone. For abdominal aortic aneurysms, the standard definition starts at 3.0 cm in diameter, and surgical repair is typically considered once the aneurysm reaches 5.0 to 5.5 cm or is growing rapidly.
Putting Your Risk in Context
The risk factors that matter most are the ones that overlap. A 68-year-old man who smoked for 20 years and has uncontrolled high blood pressure carries a meaningfully different risk profile than someone the same age with none of those factors. Smoking and hypertension are the two you can do the most about. Blood pressure management slows the arterial remodeling that leads to aneurysm growth, and smoking cessation reduces rupture risk enough that former smokers eventually approach the baseline risk of people who never smoked.
If you’re a man aged 65 to 75 with any smoking history, a single abdominal ultrasound screening is a straightforward, evidence-backed step. If you have a connective tissue disorder, polycystic kidney disease, or multiple family members with aneurysms, targeted screening for brain or aortic aneurysms is part of standard care for your situation.