The Dutch study, published in `Stroke: Journal of the American Heart Association`, identified eight main triggers that appear to increase the risk of intra-cranial aneurysm (IA) -- a weakness in the wall of a brain blood vessel that often causes it to balloon. If ruptures, it can result in a sub-arachnoid hemorrhage which is a stroke caused by bleeding at the base of the brain.
Other regular activities that may cause a stroke included vigorous physical exercise, straining to defecate, being startled, being angry and drinking cola, found the study.
"All of the triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture," said lead researcher Monique H M Vlak of the University Medical Center in Utrecht, the Netherlands.
"Sub-arachnoid hemorrhage caused by the rupture of an intra-cranial aneurysm is a devastating event that often affects young adults," Vlak said.
"These trigger factors we found are superimposed on known risk factors, including female gender, age and hypertension."
On alcohol use, the researches said the risk was higher shortly after drinking, but it declines quickly.
According to them, few people with IAs have symptoms before such a rupture, such as vomiting, vision problems, loss of consciousness, and especially severe headaches. But, many people show no symptoms. With the increasing use of neuro imaging techniques, more incidental aneurysms are being detected, the researchers said.
For their study, the researchers asked 250 patients with aneurysmal sub-arachnoid hemorrhage to complete a questionnaire about exposure to 30 potential trigger factors in the period shortly before their event and their usual frequency and intensity of exposure to these triggers.
They then assessed relative risk using a case-crossover design that determines if a specific event was triggered by something that happened just before it.
They found that drinking coffee has the highest (10.6 per cent) risk of getting a stroke, while vigorous exercise can increase a person`s risk by 7.9 per cent.
Similarly, a simple nose blowing increases the risk by 5.4 per cent, while sexual intercourse ups the risk by 5.4 per cent, followed by straining to defecate (3.6 per cent), cola consumption (3.5 per cent), being startled (2.7 per cent) and being angry (1.3 per cent).
Although physical activity had triggering potential, the researchers don`t advise refraining from it because it`s also an important factor in lowering risk of other cardiovascular diseases.
"Reducing caffeine consumption or treating constipated patients with unruptured IAs with laxatives may lower the risk of sub-arachnoid hemorrhage," Vlak said.
"Whether prescribing anti-hypertensive drugs to patients with unruptured IAs is beneficial in terms of preventing aneurysmal rupture still needs to be further investigated."