October 25, 2013
News Review From Harvard Medical School -- Strokes Up, Especially for Younger Adults
Strokes are rising worldwide, a new study shows. And much of the burden is falling on middle-aged adults and low- to middle-income countries. Researchers put together numbers from 119 studies to estimate strokes for the years 1990 and 2010. In that 20-year span, stroke death rates declined 36% in high-income countries and 20% in low- and middle-income countries. But the total number of first strokes rose 68%. Strokes among adults ages 20 to 64 rose from 25% to 31% of all strokes. Most of that increase occurred in the low- to middle-income countries. Illness and death linked with stroke has shifted toward people under age 75, the study found. They now account for 62% of new strokes, 45% of deaths and 72% of illness and disability. Another new study found that hemorrhagic (bleeding) strokes cause 52% of deaths and 61% of disability from stroke. This occurs even though bleeding strokes are only half as common as ischemic strokes, which are caused by a blockage of blood to the brain. Bleeding stroke rates are higher among adults under 75 and in low- and middle-income countries. The journals Lancet and Lancet Global Health published the studies. HealthDay News wrote about them October 24.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Good news and bad news. The good news is that in general the percentage of people worldwide who have strokes is decreasing. The bad news is that the total number of strokes around the world continues to increase. And the numbers of deaths and significantly disabled people also keep going up.
How can the total number of strokes around the world increase if the percentage of people having strokes has decreased? The two major reasons are population growth and increased life span in most countries around the world. Older age is a major factor that increases the risk of stroke.
One of the most worrisome trends is the increased rate of strokes in people under the age of 75. In 2010, according to the studies in Lancet and Lancet Global Health, an estimated 5.2 million strokes occurred in children, teens and adults under age 65.
Stroke rates were very different in low- and moderate-income countries, compared with high-income countries. People living in low- and moderate-income countries had an 18% increase in the rate of all strokes. In comparison, stroke rates decreased significantly in high-income countries.
Strokes occur because:
- Blood flow to part of the brain is blocked (ischemic stroke)
- A blood vessel in the brain leaks or breaks open (hemorrhagic stroke)
Ischemic strokes are more common, especially in the elderly. Hemorrhagic strokes occur about half as often. But they more often strike younger people. And these strokes caused by bleeding in the brain are linked with more disability and a higher risk of death.
Again, it was the low- and moderate-income countries that had much higher rates of hemorrhagic stroke. High blood pressure is the major factor that increases the risk of this type of stroke. Given the limited resources in many of these countries, high blood pressure is underdiagnosed and undertreated. Higher rates of smoking and heavier use of alcohol also may be contributing factors.
What Changes Can I Make Now?
Here's how to lower your risk of all types of strokes:
- Keep your blood pressure in the normal range (less than 140/90). This is the most important step.
- Lower your blood cholesterol level if it is high.
- Maintain a normal weight.
- Don't smoke.
- Eat at least 5 servings of fruits and vegetables daily.
- Stay physically active, and schedule a minimum of 30 minutes per day for dedicated exercise.
- If you drink alcohol, have no more than an average of 2 drinks per day if you are a man or 1 drink per day if you are a woman.
If you have atrial fibrillation (an abnormal heart rhythm), you and your doctor need to choose a drug that prevents clots from forming in the heart.
What Can I Expect Looking to the Future?
High-income countries will likely continue to see a fall in stroke rates. For stroke rates to decrease in low- and moderate-income countries, there will need to be an emphasis on risk factors that have just recently surfaced there.
Poor nutrition has been a major, longstanding concern for many of these countries. Only in the last few years have public health officials shifted gears to educate people on the importance of not overeating, choosing healthier foods, becoming more physically active and getting blood pressure checked.