Shingles and Stroke Risk
Study also found increased odds of heart attack, mini-stroke in older adults years after infection
To answer that question, they reviewed more than 106,000 cases of shingles in the United Kingdom and compared them to more than 213,000 people who were matched for age and sex but hadn't had shingles. For those who'd had shingles, the average time since their illness was a little over six years. The longest time since shingles was 24 years.
The researchers controlled their analysis to account for other factors that could increase stroke and heart attack risk, such as smoking history, high blood pressure, unhealthy cholesterol levels, diabetes, heart problems and obesity.
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.