Inherited Disorders that Contribute to Stroke. Some cases of atrial fibrillation may be inherited. Genetic disorders that cause connective tissue disorders are also associated with stroke from hemorrhage; they include polycystic kidney disease, Ehlers-Danlos syndrome type IV, neurofibromatosis type 1, Marfan's syndrome, and moyamoya disease.
Specific Genetic Factors Under Investigation. Specific genetic factors are under investigation. They include:
- Inherited deficiencies in protein factors C and S, which inhibit blood clotting, may be responsible for certain cases of stroke in young adults.
- A genetic mutation in a factor V Leiden may be related to blood clotting risks.
- People who have inherited a gene called apolipoprotein (Apo) E-4 may be at increased risk of stroke. This gene is also associated with Alzheimer's disease.
Mental and Emotional Factors
Stress. One survey revealed that men who had a more intense response to stressful situations, such as waiting in line or problems at work, were more likely to have strokes than those who did not report such distress. In some people, prolonged or frequent mental stress causes an exaggerated increase in blood pressure, which in turn can increase the risk for stroke.
Depression. Depression has also been linked to higher risk for stroke and lower stroke survival rates. In one study, patients with severe depression had a 73% higher risk for stroke, and those with moderate depression had a 25% higher risk than average. The risk for stroke in African Americans with depression was 160% higher than average.
Migraine and Associated Risk Factors
Studies have found that migraine or severe headache may be a risk factor for stroke in both men and women, especially before age 50. Overall, between 2 - 3% of ischemic strokes occur in people with a history of migraine. However, in patients under age 45, about 15% of all strokes (and 30 - 60% of strokes in young women) are associated with a history of migraines, particularly migraine with aura. Some evidence suggests that some strokes in these cases may actually be due to excessive activation of the nervous system and the dehydration from vomiting that occurs during a severe migraine with aura.
The actual risk itself for migraineurs is low, however. In one study, women with migraines had a 2.7% risk of stroke, with the time of greatest risk between the ages of 45 and 65. Men with migraines had a 4.6% risk, and their greatest time of risk was before age 45. In both genders, the risk diminished with age. Studies suggest specific risk factors for younger women with migraines, particularly those with auras, include taking high-estrogen oral contraceptives (OCs). (Whether progesterone-alone contraceptives carry any risk is unknown.) In migraineurs who take OCs, the risk increases with high blood pressure, smoking, or both.
Infections and Inflammation
Inflammation that occurs with various infections has been associated with stroke. One study found that patients hospitalized for stroke were three times more likely than patients without strokes to have recently been exposed to infections, usually mild ones in the respiratory tract.
Varicella Virus. Varicella zoster virus (the virus that causes chicken pox and shingles) has been associated with cerebral vasculitis, a condition in which blood vessels in the brain become inflamed. It is a very rare cause of stroke in children. The virus has also been associated with some cases of stroke in young adults.
Chlamydia Pneumonia. Some investigators suspect that some infections may produce inflammation in the arteries that can lead to stroke over time. (Similar work is underway in heart disease.) Researchers are particularly interested in Chlamydia pneumoniae, a non-bacterial organism that causes mild pneumonia in adults. Chronic infection has been linked with a higher risk for stroke, and evidence of the organism has been observed in thickened inner vessel walls of the carotid arteries in some studies. Chlamydia has also been linked to heart disease.
Periodontal Disease. A number of studies now strongly support an association between periodontal disease and cardiovascular disorders. According to a major analysis, periodontal (gum) disease is associated with a 20% higher risk for ischemic stroke and heart disease. The added risk may be even greater in adults under 65. Recent evidence points to the inflammatory response as the common element.
Peripheral Artery Disease
Peripheral artery disease (PAD) occurs when atherosclerosis affects the extremities, particularly the feet and legs. The major risk factors for heart disease and stroke are also the most important risk factors for PAD. The occurrence of such conditions in combination with PAD often signals more severe forms of heart or circulatory disease.
Other Medical or Physical Conditions Associated with a Higher Risk for Stroke
A number of medical or physical conditions may contribute to the risk for stroke:
- Sleep apnea. This common disorder, in which the throat becomes obstructed during sleep, may contribute to the narrowing of the carotid artery, appearing to increase the risk for stroke three- to six-fold.
- Pregnancy. Pregnancy carries a very small risk for stroke, mostly in women with pregnancy related high blood pressure and in those with cesarean delivery. The risk appears to be higher in the postpartum (post-delivery) period, perhaps because of the sudden change in circulation and hormone levels.
- Anti-phospholipid antibodies. Nearly 40% of young people with strokes and 10% of all stroke patients have components of the immune system known as anti-phospholipid antibodies that increase the chance for blood clots.
- Sickle-cell anemia. People with sickle-cell anemia are at risk for stroke at a young age.
- Drug abuse, particularly with cocaine and, increasingly, methamphetamine, is a major factor in the incidence of stroke in young adults.
Other Factors Associated with Stroke
Timing. Like heart attack and sudden cardiac death, stroke appears to be more common in the morning hours, perhaps due to a temporary rise in blood pressure at that time. Various studies point to a higher risk for stroke on weekends, Mondays, and holidays. The risk for hemorrhagic stroke may also be higher in the winter, particularly in older people with high blood pressure.
Height. Shorter people are at higher risk than taller individuals.
Homocysteine and Vitamin B Deficiencies. Abnormally high blood levels of the amino acid homocysteine, which occur with deficiencies of vitamin B6, B12, and folic acid, may be linked to an increased risk of coronary artery disease and stroke.
Neck Manipulation. Some studies have reported a higher risk for stroke from injury to the carotid artery after neck manipulation by a chiropractor.
Anabolic Steroids. Steroids used for body-building increase the risk.
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