Lifting Some Blame From Cholesterol
In older people, stroke risk fell with higher blood-fat levels

(HealthDay News) -- High cholesterol levels apparently don't automatically increase the risk of stroke.

British researchers analyzed 61 studies that included nearly 900,000 adults and concluded that high cholesterol lowered the risk of stroke for people in their 70s and 80s, even as it elevated their risk for heart attack.

None of the participants had heart disease at the start of the studies. As expected, the data review showed that decreases in blood cholesterol levels achieved with cholesterol-lowering statin drugs more than halved the heart disease death rate among adults age 40 to 49, decreased it by 34 percent among those age 50 to 59 and cut it by 17 percent among those age 70 to 89.

But the review found only a weak link between total cholesterol levels and the death rate from stroke among those 40 to 59 years old. And among people 70 to 89 years old, higher cholesterol levels were associated with a lower rate of death from stroke, particularly among those with a systolic blood pressure (top number in a reading) above 145 mm Hg.

The findings suggest that "there is something very odd going on" in the link between blood cholesterol and stroke-related death, said Sarah Lewington, one of the study authors and a senior research fellow at Oxford University .

"Maybe we're not measuring the right thing," she told HealthDay . "Maybe it's more complicated than that."

Lewington emphasized that "these data shouldn't make people stop taking statins, because it's been shown that statins reduce the risk of stroke." The findings were published in The Lancet .

A statistical factor might explain the apparent link between high cholesterol and lower stroke death rates among older people, two French stroke experts suggested in an editorial that accompanied the study. The combination of high cholesterol and elevated blood pressure might have killed off the most vulnerable part of the study population before their eighth decade, leaving only more robust people alive, the experts theorized.

Another expert told HealthDay that he wasn't surprised by the review's findings because stroke is a more complicated condition than heart attack, which has a single cause: buildup of fatty deposits that block a coronary artery.

Stroke has a number of causes, said Dr. Deepak Bhatt, chief of cardiology at the VA Boston Healthcare System:

• A blockage in a carotid artery (a main blood vessel to the brain)
• A rupture of an artery in the brain
• A clot in an artery in the brain
• An irregular heartbeat (called atrial fibrillation) that sends a clot to the brain.

Bhatt also noted that a person might survive a stroke but be so weakened that he or she soon dies of heart disease. In such cases, stroke isn't listed as the cause of death, he said.

All these factors "can create something of a messy picture that can lead some people to conclude that control of cholesterol is not important for stroke prevention," Bhatt said.

However, "from a patient's perspective, nothing here contradicts the fact that if they have high cholesterol, they should get it treated," he said. "It would be bad if the public gets a mixed message."

On the Web

To learn more about stroke prevention, visit the U.S. National Institute of Neurological Disorders and Stroke.

SOURCES: HealthDay News ; Sarah Lewington, Ph.D., senior research fellow, Cambridge University, England; Deepak Bhatt, M.D., chief of cardiology, VA Boston Healthcare System, and director, Integrated Cardiovascular Intervention Program, Brigham and Women's Hospital and the VA system, Boston; Dec. 1, 2007, The Lancet
Author: Robert Preidt
Publication date: Nov. 30, 2008
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