Workers who are under constant stress may start to show it in their blood pressure readings, researchers reported.

In a study that followed more than 6,719 white-collar workers for 7.5 years, Canadian researchers found that those with high job demands, and reported low levels of social support in the office, tended to have higher blood pressure than other workers.

The relationship was stronger among men than among women. As a group, men with high job strain had higher blood pressure and were at greater risk of blood pressure increases over time than those with less stressful work.

In addition, the study found that men and women who said they got little support from their bosses and co-workers seemed particularly vulnerable to the blood pressure effects of job strain.

"Our study supports the hypothesis that job strain, particularly in workers with low social support at work, may contribute to increased blood pressure," lead author Dr. Chantal Guimont of Laval University in Quebec stated.

She and her colleagues report the findings in the American Journal of Public Health.

Many studies have examined the link between cardiovascular disease and job strain -- typically defined as work with high psychological demands, but with little independence or decision-making authority. Evidence suggests that chronically stressed workers are more likely to develop heart disease, but studies looking specifically at blood pressure effects have yielded mixed results.

Theoretically, job stress might raise blood pressure by chronically activating the nervous and cardiovascular systems. On the other hand, stressed workers may have little time or energy for exercise, may eat poorly or have higher smoking rates -- though, in this study, the researchers accounted for factors like smoking, exercise habits and weight.

According to Guimont, the current findings support the notion that curbing job strain could make a difference in some workers' blood pressure. For example, she said, employers might give workers more support or more say in how they accomplish their tasks, loosen up deadline pressure, or offer more chances for learning and growth.

Studies are underway, Guimont noted, to see whether such measures work.

SOURCE: American Journal of Public Health, August 2006.