No matter your gender, stroke is a cardiovascular consequence no one asks for. Yet it happens almost 800,000 times a year, and it strikes women more often than men. Of 6.8 million Americans who have survived a stroke, 3.8 million are female. This is primarily true because stroke increases with age. Seventy-five percent of strokes occur in people over 65–and women live longer than men. By 2030 almost a fifth of Americans will be over age 65, and the majority will be women.
This has profound implications for both our society and our mothers. Stroke is the third leading cause of death for women while it ranks fifth for men. Because stroke occurs later in life for women, they are less likely to recover fully and return home to live independently, so they are more likely to be placed in a nursing home. These demographics indicate there will be approximately 200,000 more women than men living with the effects of stroke by 2030.
But age isn't the only reason women have an increased risk of stroke. Some risk factors for stroke are exclusive to women, and for this reason, the American Heart Association/American Stroke Association recently published Guidelines for the Prevention of Stroke in Women. “Emerging data suggest that men and women have a different expression and different incidence of disease,” says Louise McCullough, M.D., professor of neurology and neuroscience at the University of Connecticut Health Center and The Stroke Center at Hartford Hospital, and co-author of the guidelines. “The original guidelines didn't take into account some of the factors that are unique to women. Pregnancy and pregnancy complications being one, but also that women have poorer recovery from stroke. Women have higher rates of recurrent stroke. A lot of that is related to age.” The guidelines review risk factors unique to women (or that affect women differently) and seek to determine if there is a need for a stroke-risk score for women using female-specific factors such as pregnancy and menopause.
High blood pressure, or hypertension, is the leading cause of stroke that can be improved with lifestyle changes, and because women live longer, it affects them more than men. While women have lower blood pressure for most of their lives, it changes as women go through menopause. About 75 percent of women over age 60 have high blood pressure.
Inga Tuvesson of Ocean City, Md. had never been a big believer in doctors and medicine, even after she was diagnosed with high blood pressure. “My mother dabbled in the new age arts,” says Tia, her daughter. “She attended ‘heal your life’ workshops and read positive-thinking books.” Inga felt she didn't need to take her medicine at the prescribed times and only took it when she felt bad. Then, seven years ago, Inga had a stroke at age 73. Today she still lives with the problems caused by her stroke–aphasia (an impairment that makes it difficult to use language to communicate), limited vision and weakness on the right side of her body. “Now she is very much regimented about taking her blood pressure and other medicines on time,” Tia says. “In fact, she reminds my father about them sometimes.”
“Treating hypertension is paramount, and that's true for both women and men,” says McCullough. “Often, people don't realize that even mild hypertension is a risk because hypertension often doesn't have any symptoms. Patients come in with a blood pressure of 160 or 170, and they feel just fine, but I put them on a medicine that makes them tired or gives them a cough or is expensive. There are multiple reasons why people [don't take their medicines as prescribed], but it's exceptionally important to treat hypertension.”
Atrial fibrillation, or AFib, is another cardiac risk factor. It happens when the heart's two small upper chambers (the atria) quiver instead of beating regularly and pumping blood effectively. It's the most common heart arrhythmia, and its irregular heartbeats allow blood to pool and clot. As a result, clots can be pumped into the brain, causing a stroke called an embolic stroke.
Ischemic stroke happens when a blood vessel supplying blood to the brain is blocked. AFib increases the risk of ischemic stroke by as much as five times. Although the overall number of AFib cases is equal between men and women, AFib increases with age, so women make up about 60 percent of AFib patients over age 75. This means that elderly women have the highest risk of AFib and embolic stroke.
“Atrial fibrillation doesn't always give you symptoms,” McCullough says. “You may not be short of breath; you may not feel your heart racing. So we often send those women home with what we call a loop monitor that should pick up AFib. Especially if a woman is over 75 and she comes in with a stroke that looks like it's embolic but she's not in AFib at that moment, I will send her home with a loop monitor to look for AFib.”
Stroke: Three types
- Ischemic stroke, caused by a blockage of an artery in the brain or leading to it, results in a lack of blood flow. This accounts for about 80 percent of all strokes. There are many causes, but the leading causes are heart problems such as AFib (more common in women) and hardening of the arteries (atherosclerosis), where clots form in the heart or arteries and then block blood flow to the brain.
- Hemorrhagic stroke occurs when a weakened blood vessel ruptures. The most common cause of hemorrhagic stroke is uncontrolled high blood pressure.
- Transient ischemic attack (TIA) is caused by a temporary blood clot causing temporary symptoms of stroke. Often called a “mini stroke”, these warning strokes should be taken very seriously.
The standard treatment for AFib is blood thinners, or anticoagulants, but this can present a dilemma in treating older women. “Sometimes we are very hesitant to put elderly women on anticoagulants, especially if they're living alone and at risk for falling because that can be a complication,” McCullough says. “If you're on a blood thinner and you live alone and you fall, that could be disastrous. But elderly women are at highest risk for AFib, so it's kind of a catch-22.”
Pregnancy obviously distinguishes women and men, and pregnant women are at greater risk for stroke than women who are not pregnant. Preeclampsia is one reason. Preeclampsia is a complication that involves increased blood pressure and protein in the urine. There are no symptoms for a woman to look for, so the condition can only be diagnosed by a doctor. If left untreated, preeclampsia can become eclampsia, which can cause seizures and is very dangerous.
However, the danger from this complication does not end with the baby's birth. “We know that women who have had preeclampsia have double the stroke risk of women who didn't have preeclampsia even 40 years later,” McCullough says. In addition, there is evidence from a Taiwanese study that not only do women with preeclampsia have a higher risk of stroke, but their babies may have an increased risk, too. “There's something that goes awry in the maternal-fetal unit through the placenta,” McCullough says. “Nobody knows exactly why, but it causes this significant hypertensive response and probably damages the blood vessels, and [this damage] is long-lasting.”
Hypertension during pregnancy, even if not associated with preeclampsia, needs to be treated because “the fetus can develop what we call ‘intrauterine growth retardation,’” McCullough says. Pregnant women with high blood pressure should be started on medication. Although there are some drugs, such as ACE inhibitors, that should be avoided, there are many safe medications listed in the guidelines. The complication of developing preeclampsia or having severe hypertension is a higher risk than taking medication. Women should be screened for hypertension before trying to get pregnant.
Hormone replacement therapy
In the past, physicians thought estrogen replacement would reduce stroke risk in women because women tend not to have strokes until after menopause. “We thought that estrogen was somehow protective,” says McCullough. However, many randomized clinical trials later, that thinking was proved wrong. “As of right now, based on the data we have, hormone therapy is not recommended for the treatment or prevention of vascular disease in women,” says McCullough.
In addition, no evidence exists that premature (or other onset of) menopause causes a higher risk of stroke. Early initiation of hormone therapy within two years of menopause may reduce death from heart attack without increasing the risk of stroke. But right now, hormone therapy is only recommended for the treatment of perimenopausal symptoms like hot flashes.
A history of miscarriages also appears to increase stroke risk, and it may be related to undiagnosed clotting disorders. “These disorders put women at risk for clots, whether deep vein thrombosis in the legs or pulmonary emboli from the lungs,” McCullough says. “We know that there are a lot of clotting risk factors that can cause miscarriages. Recurrent miscarriages should be a red flag; there might have been a [blood clot] that caused the miscarriage.” Women with recurrent miscarriages are at much higher risk for stroke and should be treated, typically with an anticoagulant such as aspirin.
Overall, clotting disorders are more common in women. “This may be related to estrogen because estrogen sometimes can cause clots as well,” McCullough says.
Oral contraceptives, which typically contain estrogen, are another risk factor unique to women. Although birth control pills may not increase risk by themselves, when women taking them smoke or have hypertension, migraines or high cholesterol, it certainly increases their risk of stroke. That's what happened to Toni Amick of Columbia, S.C., who had a stroke at age 26. A blood test after her stroke showed that she had two blood disorders. “However, I was also taking birth control pills and smoking,” she says. “This combination caused me to have a stroke.” She no longer takes birth control pills and takes an anticoagulant every day.
The guidelines suggest that women planning to take birth control pills should be screened for hypertension and treated if they have it. Any other risk factors should be treated aggressively, and of course, they shouldn't smoke.
Migraine headaches are a common disorder, and most migraines do not cause strokes. However, there is an increased risk of both ischemic stroke and intracerebral hemorrhage (bleeding in the brain) when someone has a migraine with aura. (The “aura” refers to a variety of symptoms–blind spots, zigzag patterns, prickly feelings on the skin, flashing lights–that happen 5 to 30 minutes before the migraine begins.) Women with this disorder have a stroke about four times more often than men. Women who have this type of migraine and also smoke or take birth control pills increase their risk of stroke by a factor of seven. “If a woman has a migraine, she should take medicine to prevent it,” McCullough says, “but she should also stop smoking and stop taking birth control pills in order to lower her stroke risk.”
Experts estimate that 86 percent of Americans will be overweight or obese by 2030. While this is a problem for both sexes, obesity affects women more than men (35 percent compared with 32 percent).
Postmenopausal women are more likely to have abdominal obesity, and abdominal obesity has a stronger association with insulin resistance, high cholesterol, diabetes and cardiovascular disease than other body fat distributions.
Obesity is another risk factor for stroke. Obesity, defined as a body mass index, or BMI, of 30 or more, increases the risk of stroke after considering other factors such as age, physical activity, smoking, alcohol consumption, diabetes and hypertension. The larger your waist circumference, the greater your risk of having a stroke.
“Obesity increases risk for men and women, probably because it interacts with other risk factors, like metabolic syndrome, especially in the 45- to 55-year-old age groups,” McCullough says. “If you're obese, you're more likely to have other problems, including diabetes or cholesterol issues, and those all increase risk. That's why these guidelines recommend, and this is the same for men, to follow a Mediterranean-type or DASH diet–low in saturated fat, lots of fruits and vegetables. And be more active.”
Metabolic syndrome is a constellation of problems—insulin resistance, abdominal obesity, high cholesterol and high blood pressure–that affects about a third of Americans. It also appears to affect women more than men and accounts for a larger proportion of strokes in women (30 percent compared with 4 percent). “But some of the studies have been conflicting so we didn't include much in the guidelines,” McCullough says. “We really wanted to focus on things that were clearly a risk. But the emerging data suggest that, yes, women are at higher risk, especially in the perimenopausal time period [age 45 to 55].”
Women are at higher risk for stroke primarily because stroke risk increases with age, and women live longer than men. Older women can reduce their risk by being screened for AFib and then getting treated for it with blood thinners, but this strategy isn't without risk.
As for younger women, stroke is rare. However, pregnancy does increase risk, especially for women who develop preeclampsia. Birth control pills also increase the risk slightly. However, this risk rises dramatically if contraceptive use is combined with smoking.
Uncontrolled high blood pressure poses the greatest risk for women of all ages. There are lifestyle changes that may reduce blood pressure, but if they don't work, women should consider taking medication to help control their blood pressure.
There are effective lifestyle interventions for many of these problems. “They're the same for men and women and it's exactly what you expect,” McCullough says. “It's not rocket science. If you smoke, stop. If you're overweight, lose weight. If you're sedentary, try to be physically active and follow a diet that is low in saturated and trans fats, sodium (salt) and added sugars. Treat hypertension. If you have high cholesterol, oftentimes that's genetic, and we're finding that's a risk and that requires treatment with medications. Treat the things that we know are risk factors for stroke.”