It’s hard to believe that blowing your nose or drinking coffee could be deadly. But for those who — perhaps unknowingly — have an untreated brain aneurysm, these everyday actions could trigger a life-threatening stroke, a new study suggests.
Up to 1 in 15 people will develop a brain aneurysm — a dangerously weak spot in the wall of a blood vessel in the brain — during their lifetime, according to the American Society of Interventional and Therapeutic Neuroradiology. All cerebral aneurysms have the potential to rupture and bleed, but few do; the National Institute of Neurological Disorders and Stroke estimates that it happens to only about 25,000 to 27,000 people in the U.S. each year. That rupture could cause hemorrhage in the brain, which is a stroke, and 40% of cases are fatal.
Although few aneurysms rupture, the idea of having one in the first place is frightening enough. And the new study probably won’t help allay any fears.
(More on TIME.com: Study: Drinking Coffee May Lower Women’s Risk of Stroke)
Led by Dr. Monique H.M. Vlak, a neurologist at the University Medical Center in Utrecht, Netherlands, the scientists surveyed 250 patients who had a stroke after a brain aneurysm ruptured. They asked them about exposure to 30 potential triggers in the period just before the stroke. Based on the patients’ responses, the researchers identified eight stroke triggers and the percentage of hemorrhages that could be attributed to each:
• Coffee consumption (10.6%)
• Vigorous physical exercise (7.9%)
• Nose blowing (5.4%)
• Sexual intercourse (4.3%)
• Straining to defecate (3.6%)
• Cola consumption (3.5%)
• Being startled (2.7%)
• Being angry (1.3%)
The common link between these triggers is that each increases blood pressure suddenly, the researchers said. And high blood pressure is a known risk factor for stroke. However, the triggers identified in the study were all short-lived, with increased risk lasting only about an hour. Risk of stroke was also higher shortly after drinking alcohol, but decreased quickly.
(More on TIME.com: Major Triggers of Heart Attack: Alcohol, Coffee — and Sitting in Traffic)
“These trigger factors we found are superimposed on known risk factors, including female gender, age and hypertension,” said Vlak. In other words, controlling such known stroke risk factors — like quitting smoking and lowering blood pressure — should take precedence over avoiding coffee.
The study was limited by the three-week lag between the occurrence of stroke and the completion of the survey, since the gap may have affected people’s ability to recall the events leading up to the stroke.
Despite the study’s restrictions, the researchers suggest that people who know they have an aneurysm should avoid some of these triggers when possible.
(More on TIME.com: Prozac Aids Recovery from Stroke)
“I think drinking no coffee or cola and avoiding straining for defecation are easy to do and can prevent some of the subarachnoid hemorrhages,” [Vlak] told 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.”
It’s important to keep in mind that these findings do not apply to the general population, but only those with untreated brain aneurysms.
The study was published in Stroke: Journal of the American Heart Association.