"This is the first report that set out to examine perceived mental stress in a large group of men and women with a sufficient number of deaths from stroke or coronary heart disease," says Hiroyaso Iso, M.D., lead investigator of the study.

Other studies have evaluated mental stress and cardiovascular outcomes, but the main focus was not on that association, says Iso. Results from these studies have been inconsistent and non-Caucasian populations and women have been understudied.

Researchers analyzed data from the 73,424 people (30,180 men and 43,244 women) between the ages of 40 and 79 years enrolled in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk. All participants had been given a baseline health screening and a lifestyle questionnaire that asked, "What is the level of stress in your daily life?" Participants were followed for about eight years. There were 778 cardiovascular deaths among the men and 643 among the women.

Iso and collaborators excluded data on participants for whom there was not a valid lifestyle questionnaire and subjects who had a previous history of stroke, coronary heart disease, or cancer.

The researchers report that 8,656 women and 6,891 men reported high mental stress. After adjustment for cardiovascular risk factors and psychological variables, women in the high-stress group had 2.24 times greater risk for stroke and 2.28 times greater risk for coronary heart disease. They also had 1.64 times the risk of any cardiovascular death.

High-stress women were about five years younger, more educated, more sedentary in lifestyle, had lower mean values of body mass index, and were more likely to have a history of hypertension or diabetes than women who reported low mental stress. These women also smoked more and were more likely to work full time. In ratings on psychological variables, high-stress women were more likely to be angry, to be in a hurry, to feel hopeless, and to feel unfulfilled.

In men, there was similar association between mental stress and myocardial infarction. Men reporting medium or high mental stress had 1.74 times greater risk of myocardial infarction after adjustment for cardiovascular risk factors.

"Ideally, clinical trials would be the best way to test whether interventions to reduce mental stress make a difference in cardiovascular disease," says Iso.