"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. Iso is a professor in the department of public health, Institute of Community Medicine, at the University of Tsukuba, Ibaraki-ken, Japan.
Other studies have evaluated mental stress and cardiovascular outcomes, but that wasn't their main focus, says Iso. Results from these studies also 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 enrolled in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study). All enrollees had been given a 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 adjusting 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, had lower mean values of body mass index and were more likely to have a history of hypertension or diabetes than women reporting 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, be in a hurry, feel hopeless and feel unfulfilled.
In men, there was similar association between mental stress and heart attack. Men reporting medium or high mental stress had 1.74 times greater risk of heart attack after adjusting 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.
Co-authors are Chigusa Date, M.D.; Akio Yamamoto, M.D.; Hideaki Toyoshima, M.D.; Naohito Tanabe, M.D.; Shogo Kikuchi, M.D.; Takaaki Kondo, M.D.; Yoshiyuki Watanabe, M.D.; Yasuhiko Wada, M.D.; Teruo Ishibashi, M.D.; Hiroshi Suzuki, M.D.; Akio Koizumi, M.D.; Yutaka Inaba, M.D.; Akiko Tamakoshi, M.D.; and Yoshiyuki Ohno, M.D.
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