Are You at Risk?

Key Factors Influencing Aneurysm Development

Understanding the factors that contribute to aneurysm formation and rupture is crucial for assessing personal risk and guiding preventative strategies like screening for aneurysms.

These factors can be broadly categorized into those that cannot be changed (non-modifiable) and those that can be influenced by lifestyle choices or medical intervention (modifiable).

Unchangeable Risk Factors

These are inherent characteristics or conditions that increase susceptibility to aneurysms:

Age: The risk for most types of aneurysms increases significantly with advancing age. Abdominal aortic aneurysms (AAAs) become notably more common after age 60-65. Brain aneurysms are most frequently diagnosed between the ages of 35 and 60, although they typically begin developing after age 40. This age-related increase is partly due to the cumulative effects of other risk factors like atherosclerosis and hypertension, as well as the natural deterioration of blood vessel strength and elasticity over time.

Gender:

Gender-related risk varies depending on the aneurysm type. Men face a substantially higher risk of developing AAAs, with prevalence rates four to six times higher than in women.   Popliteal artery aneurysms (PAA) also show a strong male predominance. Conversely, women are more likely to have brain aneurysms, with a roughly 3:2 female-to-male ratio.

Furthermore, women, particularly those over 55 or post-menopause, appear to have a higher risk of brain aneurysm rupture compared to men. For AAAs, while less common in women, some evidence suggests they may rupture at smaller diameters and women may experience higher mortality rates following repair surgery compared to men. Thoracic aortic aneurysms (TAAs) seem to affect both sexes more equally.

Genetics and Family History:

A family history of aneurysms is a significant and well-established risk factor. Having a first-degree relative (parent, sibling, or child) with an AAA increases an individual’s risk by approximately 2 to 5 times compared to the general population. For brain aneurysms, having two or more first-degree relatives with a history of brain aneurysm or subarachnoid hemorrhage significantly elevates risk (2-3 times higher) and is a key indicator for considering screening.

A family history of aneurysm rupture also increases an individual’s own risk of rupture if they develop an aneurysm. Research has identified specific genetic variations and chromosomal locations (like 9p21) associated with increased susceptibility to aneurysms and related vascular diseases. This strong familial link underscores the importance of knowing one’s family medical history.

Inherited Conditions:

Certain genetic disorders that affect connective tissues or blood vessel integrity dramatically increase the risk of developing aneurysms, often at a younger age. These include:

Marfan Syndrome and Ehlers-Danlos Syndrome (vascular type): These connective tissue disorders weaken arterial walls, predisposing individuals particularly to TAAs and aortic dissections.

Autosomal Dominant Polycystic Kidney Disease (ADPKD): Individuals with ADPKD have a significantly higher prevalence of brain aneurysms (estimated 9-12% vs 2-3% in the general population) and an increased risk of rupture.

Other conditions: Loeys-Dietz syndrome, Neurofibromatosis type 1, Tuberous Sclerosis Complex, Turner syndrome, and Coarctation of the Aorta have also been linked to increased aneurysm risk.

Bicuspid aortic valve disease (having an aortic valve with two leaflets instead of the usual three) is a risk factor for ascending aortic aneurysms and dissections.

Race/Ethnicity: Some racial and ethnic differences in aneurysm prevalence and risk have been observed, although the reasons are complex and likely involve a combination of genetic, environmental, and socioeconomic factors.

AAAs are generally reported to be more common in Caucasians than in individuals of African descent. Conversely, the risk of brain aneurysm rupture may be higher in African Americans and Hispanics compared to Caucasians. Broader cardiovascular disease rates are also disproportionately higher in Black populations.

Modifiable Risk Factors

These are factors related to lifestyle and health conditions that can be changed or managed to reduce aneurysm risk:

Smoking: This is arguably the single most important modifiable risk factor, particularly for the development, growth, and rupture of AAAs. A history of smoking is estimated to account for about 75% of all AAAs.

Smoking damages blood vessel linings, promotes inflammation, contributes to atherosclerosis, and increases blood pressure. It is also strongly linked to brain aneurysm formation and rupture.

Even having smoked in the past significantly increases risk. Quitting smoking is paramount for reducing risk, and cessation support (counseling, nicotine replacement therapy, medication) should be sought.

High Blood Pressure (Hypertension): Uncontrolled high blood pressure is a major contributor to both the formation and rupture of nearly all types of aneurysms. Hypertension exerts constant excessive force on artery walls, accelerating damage and weakening, especially in susceptible areas.

Effective blood pressure control through lifestyle changes and, if necessary, medication is critical for prevention and for managing diagnosed aneurysms. A target blood pressure of less than 130/80 mmHg is generally recommended for cardiovascular disease prevention.

Atherosclerosis and High Cholesterol: The buildup of plaque in arteries (atherosclerosis) weakens vessel walls and is a primary cause or risk factor for AAAs and PAAs.   Managing blood cholesterol levels, particularly lowering LDL (“bad”) cholesterol, is an important preventative measure.

Statin medications are often first-line therapy for elevated LDL and primary prevention of atherosclerotic cardiovascular disease (ASCVD) based on risk assessment. For diagnosed, unruptured aneurysms, cholesterol-lowering medications can help slow growth and reduce pressure on the artery wall.   

Interestingly, while high cholesterol is linked to atherosclerosis, the specific association between LDL cholesterol and AAA risk might be less direct compared to its role in coronary artery disease, suggesting potentially distinct mechanisms in AAA development.

Diabetes Mellitus: The role of diabetes in aneurysm risk is complex. Diabetes is a major risk factor for general atherosclerosis and cardiovascular disease. However, several studies have paradoxically found that diabetes may be associated with a lower incidence or risk of developing AAAs.

The reasons for this potential protective effect are not fully understood but might involve differences in inflammation or matrix degradation pathways compared to typical atherosclerosis. Regardless of this specific nuance for AAA, managing diabetes remains crucial for overall vascular health and reducing other cardiovascular risks.

Obesity and Physical Inactivity: These factors contribute significantly to the development of hypertension, high cholesterol, diabetes, and atherosclerosis, all of which increase aneurysm risk. Maintaining a healthy weight through diet and regular physical activity is therefore recommended.

Guidelines typically suggest at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week, combined with muscle-strengthening activities. (Note: An “obesity paradox,” where being overweight might offer some protection against brain aneurysm development/rupture, has been suggested but requires more research and does not negate the overall health risks of obesity).

  • Alcohol Consumption: Excessive alcohol intake is considered a risk factor. Moderation is advised, generally defined as no more than two drinks per day for men and one drink per day for women.
  • Illicit Drug Use: Stimulant drugs, particularly cocaine and amphetamines, can dangerously elevate blood pressure and increase the risk of aneurysm formation or rupture. Avoiding these substances is crucial.
  • Inflammation: Chronic inflammation is increasingly recognized as playing a role in the weakening of blood vessel walls. Dietary and lifestyle approaches aimed at reducing systemic inflammation may be beneficial.

The significant impact of modifiable factors like smoking and hypertension across different aneurysm types strongly suggests that addressing these two areas offers the greatest potential for reducing the overall burden of aneurysm disease.

Aneurysms Statistics in the United States

Understanding the prevalence, incidence, and outcomes associated with aneurysms in the US population highlights the public health significance of this condition. Statistics vary considerably depending on the type and location of the aneurysm.

Brain Aneurysms: Data primarily from the Brain Aneurysm Foundation (BAF) and neurological institutes paint a detailed picture:

  • Prevalence: An estimated 6.7 million people in the US have an unruptured brain aneurysm, translating to approximately 1 in 50 individuals. Other estimates place the prevalence in the range of 2-6% of the healthy population.   The average age at detection is around 50 years. 
  • Incidence of Rupture: While many brain aneurysms remain stable, the annual rate of rupture is estimated at 8 to 10 per 100,000 people. This equates to about 30,000 brain aneurysm ruptures occurring in the US each year. Strikingly, this means a brain aneurysm ruptures approximately every 18 minutes.
  • Mortality and Morbidity: The consequences of rupture are severe. About 50% of ruptured brain aneurysm cases are fatal. An estimated 15% of individuals die before reaching the hospital, often due to massive initial bleeding. Among those who survive the rupture, a significant majority—approximately 66%—suffer from permanent neurological deficits. This high rate of long-term disability represents a substantial hidden burden beyond mortality, impacting quality of life and incurring significant healthcare costs and lost productivity (estimated at $150 million in lost wages for survivors and caretakers in one year, based on a 2004 study). Overall, aneurysmal subarachnoid hemorrhage accounts for roughly 0.4-0.6% of all deaths from any cause.
  • Misdiagnosis: Accurate and timely diagnosis is critical, yet misdiagnosis or delays occur in up to a quarter of patients initially seeking medical attention for a rupture. Failure to perform appropriate brain imaging (like a CT scan) is the reason in three out of four misdiagnosed cases. The cost of treating a ruptured aneurysm is substantially higher than treating an unruptured one.
  • Demographics: Brain aneurysms are more prevalent in women (3:2 ratio). Women over age 55 face about 1.5 times the risk of rupture compared to men. African Americans and Hispanics may have approximately double the risk of rupture compared to Caucasians.18 The condition is most prevalent in individuals aged 35 to 60.

Aortic Aneurysms: Statistics from the Centers for Disease Control and Prevention (CDC), American Heart Association (AHA), and research studies reveal:

  • Mortality: In 2019, aortic aneurysms (both types) and aortic dissections were cited as the cause of 9,904 deaths in the US. Approximately 59% of these deaths occurred among men. AAA is recognized as the 10th leading cause of death for Caucasian men aged 65-74 and the 3rd leading cause of sudden death in men over 60. The mortality rate following a ruptured AAA is alarmingly high, estimated at around 81% overall.
  • Prevalence (AAA): The prevalence of AAA increases sharply with age. It affects about 1% of men aged 55-64, but this figure rises with each decade. Overall average prevalence is estimated around 2.8%, climbing to over 5% in men older than 75, and reaching nearly 10% in men over 75 who have a history of smoking. As noted earlier, AAAs are 4-5 times more common in men than women and more prevalent in Caucasians. 
  • Prevalence (TAA): Thoracic aortic aneurysms are less common, with an estimated prevalence of around 0.16%. Unlike AAA, TAA affects men and women at similar rates.
  • Smoking Link: The connection between smoking and AAA is profound. A history of smoking is implicated in approximately 75% of all diagnosed AAAs.

Peripheral Aneurysms (Popliteal Artery Aneurysm Focus):

  • Incidence/Prevalence: PAAs are the most common type of peripheral aneurysm. However, they are still relatively rare in the general population, with incidence estimates ranging from 0.1% to 2.8%. They are much more common in men (some studies report incidence rates of 7 per 100,000 men versus 1 per 100,000 women, or over 95% male prevalence in surgical series). Among patients diagnosed with an AAA, the prevalence of a concurrent PAA is significantly higher, ranging from 3% to 11%.
  • Complications: Rupture is an infrequent complication of PAA (occurring in 2-5% of operated cases). The major threat is thrombus formation within the aneurysm or embolization of clots to the lower leg, occurring in roughly 30% of untreated cases and leading to acute limb ischemia (ALI). ALI carries a significant risk of limb loss, although amputation rates have improved with modern treatment, they may still be around 15% or higher in some series.

The differing prevalence rates and risk group concentrations between aneurysm types significantly influence public health approaches. For instance, the high concentration of AAA risk in older male smokers makes targeted screening feasible and recommended by bodies like the US Preventive Services Task Force (USPSTF). In contrast, while unruptured brain aneurysms are more common overall, the lower individual risk of rupture for any given aneurysm makes universal screening impractical, leading to guidelines focusing only on very high-risk subgroups.

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