Researchers - again - pinpoint why stress kills.

2004 MAR 4 - (NewsRx.com & NewsRx.net) -- One prevailing argument for marriage may well be that studies show married people are less depressed than their single counterparts.

Behind this string of scientific reasoning for matrimony is a proven fact: The prevalence of depression in patients with coronary artery disease (e.g., myocardial infarction and heart failure) is approximately five times that of the general population.

Major depression is a significant predictor of mortality after myocardial infarction. Its predictive ability on subsequent cardiovascular events, for example, myocardial infarction, arrhythmias, ischemia or sudden cardiac death, is comparable to that of left ventricular dysfunction, previous myocardial infarction and smoking. Even more alarming is the finding that depression is a significant risk factor for coronary artery disease in patients without a history of heart disease. In other words, the risk for a heart attack or other cardiac disease for depressed but otherwise healthy patients is similar to the risk for patients with established cardiovascular disease.

Gender does play a role. Psychological depression is a common mood disorder affecting 2-3% of males and 5-9% of females. Depression is the leading cause of disability worldwide (quantified by years lived with a disease) and is exceeded only by coronary artery disease as the leading cause of disability in the United States. So, in addition to all the social and medical costs of depression, the disorder is considered a risk factor for coronary artery disease.

Why? Past studies to establish the link between cardiac disease and depression have focused on hypothalamic-pituitary-adrenal axis dysfunction associated with increased sympathetic activation, an imbalance in parasympathetic and sympathetic inputs to the heart (i.e., increased sympathetic tone and/or decreased parasympathetic tone), manifest as reduced heart rate variability, and altered serotonin activity affecting platelet function.

Scientists have noted an important interaction between stress and ventricular arrhythmias, or loss of rhythm to the heart. This relationship has been supported by animal studies and in observation of some human patients with postmyocardial infarction, where the presence of depression in combination with premature ventricular complexes greatly increases the likelihood of a recurrent heart attack.

However, none of these suppositions is well established. A team of University of Iowa researchers set out to ascertain whether an increased susceptibility to life-threatening cardiac arrhythmias in depressed patients influences the risk of morbidity and mortality in coronary artery disease. The findings of their research were reported by Angela J. Grippo and colleagues from the University of Iowa in ...