Cholesterol-Stroke Relationship Puzzles Researchers

By Ed Edelson
HealthDay Reporter
Saturday, December 1, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

FRIDAY, Nov. 30 (HealthDay News) -- The link between high cholesterol and heart disease is clear to most in the medical community, but a new British study finds the connection between cholesterol levels and stroke is a bit more murky.

In fact, for people in their 70s and 80s, the review found that high cholesterol actually lowered stroke risk, even as it boosted the odds for heart attack.

The analysis of 61 studies showed that "there is something very odd going on" in the link between blood cholesterol and stroke mortality, said study author Sarah Lewington, a senior research fellow at Oxford University.

However, "these data shouldn't make people stop taking statins, because it's been shown that statins reduce the risk of stroke," she said.

Statins include cholesterol-lowering drugs such as Crestor, Lipitor and Pravachol.

In its review, published in the Dec. 1 issue of The Lancet, Lewington's team surveyed data on almost 900,000 adults who had no heart disease at the start of the studies.

As expected, they found that the drop in blood cholesterol levels achieved with statin therapy more than halved the heart disease death rate in the 40-49 age group, decreased it by 34 percent for those aged 50-59, and achieved a 17 percent reduction in the 70-89 age group.

The reduction in heart deaths was lower in people with high blood pressure, since the effects of blood pressure and cholesterol are independent of each other.

In contrast, total cholesterol levels were related only weakly to stroke mortality for the 40-59 age group. That relationship could be explained almost entirely by cholesterol's association with blood pressure, the analysis found.

And in the 70- to 89-year-old age group, higher cholesterol levels were actually associated with a lower stroke death rate, particularly for people with a systolic blood pressure (the top number in a reading) above 145 mm/Hg -- a finding that left Lewington puzzled.

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