Shingles and Stroke Risk
Study also found increased odds of heart attack, mini-stroke in older adults years after infection
In people who'd had shingles when they were over 40, the risk of stroke was not increased, the investigators found. However, the risks of heart attack and mini-strokes were slightly higher.
For those who had shingles before age 40, however, risk of stroke was 74 percent higher compared to those who hadn't had shingles. Their risk of mini-stroke was 2.4 times higher and their risk of heart attack was increased by 50 percent, the study revealed.
Breuer said the reason that having had shingles might increase a person's risk of stroke, mini-stroke or heart attack is that shingles can also cause an inflammation of certain blood vessels. In people who already have risk factors for stroke or heart attack, this inflammation would add to that risk, she explained.
However, two U.S. doctors suggested that stroke risk posed by shingles might be overstated.
"The risk may be higher in people under 40 because of all the confounding factors they looked at," said Dr. Kenneth Bromberg, director of the Vaccine Research Center at the Brooklyn Hospital Center in New York City. "Maybe more attention is paid to factors like diabetes and [high blood pressure] in people over 40. Maybe if you deal with the risk factors, the zoster might be less of an issue."
Added Dr. Len Horovitz, an internal medicine physician at Lenox Hill Hospital in New York City: "Clearly, this study found an association between stroke and shingles in people under 40, but it's unclear what the exact mechanism is.
"This study raises more questions than it answers," Horovitz said. "Would these findings be the same in the U.S.? These researchers looked at a British population. Do we need to be more vigilant about screening people who've had early shingles? Is it really a risk factor for stroke? Would the vaccine have any effect?"
Study author Breuer said it's unclear what effect the shingles vaccine might have on the increased risk of stroke.
In the meantime, all three experts advised that anyone who's had shingles before age 40 be screened for stroke and heart attack risk factors, such as diabetes, high blood pressure and unhealthy cholesterol levels.