By Steven Reinberg
The researchers said a demanding job in which you have little or no control over your work environment is a formula that can increase the risk of dying early whether you suffer from heart disease or not. But that risk jumps 68 percent for men with heart disease or diabetes, the investigators found.
"These findings suggest that working very hard might not be a good idea for people with a serious cardiometabolic disease, such as those with diabetes, coronary heart disease or a history of stroke," said lead researcher Mika Kivimaki, chair of social epidemiology at University College London.
Physiological stress response is a normal reaction to a challenge in work and private life, but can involve a number of changes that might affect heart function, clotting and plaque in blood vessels, he explained.
"These changes, in turn, can trigger a fatal heart attack or stroke," Kivimaki added. And work-related stress may be particularly harmful for men with diabetes or a history of heart attack or stroke, he said.
"We found the stress-mortality link in men but not in women, which is consistent with the fact that atherosclerosis [hardening of the arteries] is more common in working-aged men than women," Kivimaki noted.
Dr. Satjit Bhusri, a cardiologist at Lenox Hill Hospital in New York City, said the mind has a direct link to the heart. "There is a mind-heart loop, which can affect your heart," he said.
Bhusri believes that reducing work stress can reduce the risk to the heart. But reducing work stress might mean quitting a stressful job, he noted.
"I've had patients who have retired or quit their job," Bhusri said. "What you have to realize is that your job is a slice of the whole pie of your life. And without a life, there are no slices," he said.
To reduce stress, Bhusri promotes mediation, yoga and exercise. "More importantly, if it's the job that's toxic, get rid of the job," he advised.
For the study, Kivimaki and his colleagues collected data on more than 100,000 men and women from Finland, France, Sweden and the United Kingdom, including more than 3,400 who had heart disease and diabetes. At the start of the study (between 1985 and 2002), participants completed a questionnaire on their lifestyle and health.
Over an average of nearly 14 years, the researchers tracked participants' medical records. During that time, more than 3,800 individuals died.
The investigators looked at two types of work stress: job strain -- having high work demands and little control over them; and effort-reward imbalance -- putting in lots of effort, but getting little reward.
After Kivimaki's team took into account socioeconomic status and some lifestyle factors -- including high blood pressure, high cholesterol, smoking, obesity, physical inactivity and high alcohol consumption -- it found that men with heart disease or diabetes who had job strain had a 68 percent greater risk of premature death than men who had no job strain.
This increased risk was seen in men who were being treated and had achieved their blood pressure and cholesterol targets. The risk was also seen in men with a healthy lifestyle, including being of normal weight, being physically active, not smoking and not drinking heavily.
No association was seen, however, between a risk for premature death and effort-reward imbalance in men with heart disease or diabetes. The study did not prove a cause-and-effect link between the two.
Neither type of work stress was linked with an increased risk of dying among healthy or unhealthy women, the findings showed.
Stress may affect the body in several ways, including changing natural responses to stress through higher levels of the stress hormone cortisol, which increases glucose production and limits the effect of insulin, thereby worsening diabetes, the study authors said.
In addition, stress can increase inflammation that can raise blood pressure and affect clotting, thus increasing the risk of heart problems in people who already have hardening of the arteries.
Because the researchers measured stress only at the start of the study, they could not take into account changes in the severity of diseases over time. They also did not take into account blood pressure or cholesterol levels in all the participants, which might lead to an overestimation of the effect of job strain.
In addition, people with more severe disease tended to work fewer hours, which might explain why no association between effort-reward imbalance and risk of premature death in men with heart disease or diabetes was seen, the researchers said.
The report was published online June 5 in the journal The Lancet Diabetes & Endocrinology.