LONDON, Oct. 8 -- Stormy relationships may increase long-term wear and tear on the heart physically as well as emotionally, leading to a modestly increased risk of coronary events.
Men and women who reported the most conflict in their closest personal relationship were 34% more likely to have a heart attack or angina over the subsequent 12 years than those with the least amount of conflict, according to a large cohort study in the Oct. 8 issue of the Archives of Internal Medicine.
However, emotionally supportive relationships were not linked to coronary events for good or ill, reported Roberto De Vogli, Ph.D., M.P.H., of University College London, and colleagues.
"The possibility that negative close relationships are more powerful predictors of health than other aspects of social support is consistent with previous research findings indicating that individuals tend to mentally replay negative encounters more than they replay positive ones," the researchers wrote.
Stressful aspects of intimate relationships may also be more important to health because they activate stronger emotions -- worry and anxiety -- with consequently stronger physiological effects, they said.
Many previous studies have linked social relationships to better cardiovascular health. However, findings for some aspects of relationships have been contradictory, and a previous longitudinal study of older adults showed a longer-term impact on mood from negative social exchanges than from positive ones.
So the researchers analyzed a prospective cohort of British civil servants working in London offices ages 35 to 55 from 1985 through 1988 in the Whitehall II study. The analysis included 9,011 respondents (2,897 women) who completed a questionnaire on close personal relationships in phase 1 (1985-1988) or phase 2 (1989-1990) of the study and had no history of coronary events.
Among the 8,499 participants with complete data, 589 experienced an incident fatal myocardial infarction, nonfatal MI, or angina as determined from clinical records over an average follow-up of 12.2 years.
The researchers found a dose-response association after controlling for age, sex, marital status, employment grade, obesity, hypertension, diabetes, cholesterol level, social support, and source of emotional and practical support. About a third of participants in each tertile were married or co-habiting.
Participants who ranked in the top third of the cohort for a high level of adverse exchanges and conflict in their closest relationship were 1.34 times more likely to experience a coronary event than were those in the lowest tertile (95% confidence interval 1.10 to 1.63).
Those with a lower level of these negative aspects in their closest relationship were at less risk, although still elevated compared with individuals in the lowest tertile (hazard ratio 1.19, 95% CI 0.97 to 1.46).
Negative emotions appeared to be part of the mechanism for this effect. Further adjustment of the model for negative mood and depression attenuated the associations for participants in the highest tertile (HR 1.25, 95% CI 1.02 to 1.55) and the intermediate tertile (HR 1.16, 95% CI 0.94 to 1.42).
"Our findings partially support the hypothesis that negative emotions may mediate the relationship between adverse negative relationships and heart disease," Dr. De Vogli and colleagues wrote.
However, additional adjustment for work stress (job demands and job control) and health-related behaviors (exercise, smoking, alcohol intake, and fruit and vegetable consumption) left the associations essentially unchanged.
Notably, though, confiding in and receiving emotional support from a significant other was not associated with incident coronary events for even the highest tertile of support compared with the lowest (HR 1.05, 95% CI 0.86 to 1.28).
Nor was practical help or support associated with incident coronary events for either the intermediate (HR 1.17, 95% CI 0.95 to 1.44) or the highest tertile (HR 1.01, 95% CI 0.83 to 1.24) compared with those who got the least support.
Women and lower income participants were more likely to report negative interactions in their closest relationship, but there was no statistically significant interaction with coronary events for either.
The researchers noted that depression, low self-esteem, and anger "have been found to influence coronary heart disease through the cumulative 'wear and tear' on organs and tissues caused by alterations of autonomic functions, neuroendocrine changes, disturbances in coagulation, and inflammatory and immune responses."
Although British civil servants may not be representative of the general population, the investigators said the findings are likely generalizable to the majority of the working population who have office jobs.