May 5, 2011 -- For those at risk, common activities such as drinking coffee, having sex, or blowing the nose could trigger a stroke, according to new research from the Netherlands.
"For the general population our findings do not apply,'' says researcher Monique H.M. Vlak, MD, a neurologist at the University Medical Center in Utrecht, Netherlands.
It applies, she tells WebMD, to those who have an untreated brain aneurysm. This is a weakness in the wall of a blood vessel in the brain. It often causes the wall to balloon out. If it ruptures, it can lead to a stroke known as a subarachnoid hemorrhage. It involves bleeding between a membrane that covers the brain and the brain.
While 2% of the population has this brain aneurysm, few rupture, according to Vlak.
The study is published in Stroke: Journal of the American Heart Association.
Next, Vlak calculated what is known as population-attributable risk. This is the percent of these strokes that can be attributed to a single trigger. Coffee and vigorous exercise were linked to the highest risk.
All these triggers, Vlak tells WebMD, are superimposed on known risk factors for stroke, such as advancing age or having uncontrolled high blood pressure.
The risk related to the specific triggers is also short-lived, she says. "The risk due to these trigger factors only lasts one hour."
She believes the common mechanism for the triggers is the temporary increase in blood pressure produced by all of them.
Vlak says people who know they have an untreated aneurysm should avoid at least some of the triggers when possible.
"I think drinking no coffee or cola and avoiding straining for defecation are easy to do and can prevent some of the subarachnoid hemorrhages," she tells WebMD. "However, we do not advise patients to refrain from physical exercise, since this is also an important factor in lowering the risks of other cardiovascular diseases."