People who have high-stress jobs may have an increased risk of stroke, according to a new analysis of previous research.

In their analysis, researchers looked at six studies that involved a total of nearly 140,000 people ages 18 to 75, and examined the relationship between work stress and people's risk of stroke. The studies were between three and 17 years long.

The researchers found that people who had high-stress jobs were 22 percent more likely to experience a stroke than those who had low-stress jobs.

Moreover, those with high-stress jobs were 58 percent more likely to have an ischemic stroke, which is the most common type of stroke, caused by a blockage of blood flow in the brain, compared to people with low-stress jobs. [11 Tips to Lower Stress]

"These results revealed that being exposed to high-stress jobs was associated with an increased risk of stroke, especially for ischemic stroke," said study author Dr. Yuli Huang, of Southern Medical University in Guangzhou, China.

When the investigators looked at the participants' gender, they found that women with high-stress jobs were 33 percent more likely to have a stroke than those with low-stress jobs.

The researchers did not find a link between having a high-stress job and an increased risk of stroke when they only looked at men. However, this may be due to the limited number of studies included in the analysis, the researchers said.

People tend to experience high levels stress at their job when they have little control over what they have to do, are under high time pressure and have to coordinate a lot of tasks, the researchers said. Examples of such jobs include working as waiters and nursing aides, whereas examples of low-stress jobs include working as natural scientists and architects.

The study showed an association, not a cause-and-effect relationship between high levels of job stress and an increased risk of stroke.

However, the researchers suspect that "work stress may foster unhealthy behavior such as smoking, reduced physical activity, lower help-seeking behavior and poor eating habits — all of which are also important risk factors for stroke," Huang told Live Science.

Moreover, work-related stress has also been linked with certain cardiovascular risk factors such as high body mass index, impaired metabolism of a sugar called glucose and abnormal levels of fats in the blood, which are also risk factors for stroke, Huang said.

Of the six studies included in the analysis, five adjusted the results to take the participants' ages into account, but "most of the included studies were not adequately adjusted for other risk factors," the authors of the new analysis noted.

"We think further studies are needed to evaluate whether job stress directly increases the risk of stroke or whether other concurrent risk factors are responsible for the increased risk observed," Huang said.

Dr. Jennifer J. Majersik, an associate professor of neurology at the University of Utah in Salt Lake City who was not involved in the new research, said the studies included in the analysis did not always measure the participants' metabolism or inflammation levels, which may also mediate people's risk of stroke.

"Once there is further clarity on this issue, high job strain may be considered an independent stroke risk factor in the future — and one that is potentially modifiable," Majersik said, writing in an editorial that was published in the journal along with the study.

Employers can help lower workers' stress levels, for example, by allowing them greater latitude in making their own decisions at work and embracing flexible working arrangements such as telecommuting, she said.

The new analysis was published today (Oct. 14) in the journal Neurology.

Follow Agata Blaszczak-Boxe on Twitter. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.