(Reuters Health) — People who have demanding jobs and job strain are more likely to suffer one type of stroke, a review of previous studies suggests.
Job strain has been linked to heart attack risk in the past, but not necessarily to stroke.
"Previous studies on the association between job strain and stroke have showed mixed results, with some studies showing an association and others not," said lead author Eleonor I. Fransson of the School of Health Sciences at Jönköping University in Sweden, in email to Reuters Health.
In this new analysis, which pooled the results of 14 earlier studies from Europe, people with job strain had an increased risk of so-called ischemic stroke. Ischemic strokes happen when the brain doesn't get enough oxygen — when, for example, the arteries are clogged.
Fransson, senior author Mika Kivimäki of University College London, and their coauthors used data from 14 European studies between 1985 and 2008. Altogether, almost 200,000 adults filled out questionnaires about job strain. The studies lasted nine years on average.
Those with a demanding job and little control over their work environments were categorized as having high 'job strain.' This accounted for 13 to 22 per cent of people, depending on the original study.
In general, out of every 100,000 people in Europe, each year 115 men and 75 women have an ischemic stroke, earlier research has shown.
In the new study, the risk of ischemic stroke was about 24 per cent higher for people in the job strain group than for the others.
There was no difference in risk of hemorrhagic stroke, another common type, in which a blood vessel ruptures and leaks blood into the brain.
High blood pressure, diabetes, high cholesterol, and family history of stroke are all important risk factors, but this data was not available for most people in the new study.
The researchers accounted for basic socioeconomic status, which they used as a stand-in for other health risk factors, which lessened the increase in ischemic stroke risk for those with stressful jobs.
"This present study is good contribution but of course the results present more questions," according to Susanna Toivanen, associate professor of sociology at the Center for Health Equity Studies in Stockholm, Sweden, who was not part of the new analysis.
Some strokes may have a genetic component, which may be why the researchers did not find an association with hemorrhagic stroke, Toivanen told Reuters Health by phone.
"The classification is not so exact and they don't discuss these different types of hemorrhagic stroke," she said.
This and other studies do not necessarily prove that stressful jobs cause strokes, Fransson noted.
"However, the association is plausible because stress might cause release of stress-related hormones, which in turn affect the metabolic, immunological and cardiovascular systems," she said. Ischemic stroke, like heart attack, is closely linked to atherosclerosis, the 'hardening of the arteries,' she said.
In any case, Fransson and Tovianen agreed that job strain is hard for an individual to change, even if it is increasing his risk for stroke.
"Here we have a very big issue because it's employers' responsibility to see that working conditions are healthy," Tovianen said. "Individuals can't control this."
Stress is only one of the potential factors at play with stroke risk, Fransson noted.
"The recommendations are to keep track of your blood pressure, do not smoke, eat well, keep a healthy weight and exercise," Fransson said. "Along with that it may also be good to try to avoid long periods of stress, but we do not currently have evidence from interventions to prove this."