The effects of lipids or of high blood pressure on cardiovascular (CV) mortality have been carefully elucidated and most people are aware of them. The impact of stress on CV health is less widely known. But modern research leaves little doubt that heart health is highly impacted by one’s psychological state. The longitudinal study known as INTERHEART, involving more than 29,000 people in 52 countries, found nine with a demonstrable impact on CV health: dyslipidemia, high blood pressure, cigarette smoking, diabetes, obesity, stress, lack of daily exercise, inadequate intake of fruits and vegetables, and alcohol intake.1 The researchers attributed 90% of first myocardial infarctions (MIs) to these nine risk factors.
Only smoking and the ApoB/apoA1 genes were stronger predictors of heart attack than psychosocial stress. The effect size of stress was comparable to that of hypertension or abdominal obesity, and it was found in all societies studied, at all ages and in both sexes.
Beware of bad relationships
Stress can come in many forms, ranging from loss of a spouse or a job, retirement, financial difficulties or loneliness. INTERHEART found that all of these can increase the chances of a cardiac event. Bad personal relationships definitely increase stress levels. A study led by Dr. Roberto De Vogli found that people reporting a negative close relationship ran a 34% higher risk of a coronary event in 12 years of follow-up.2 Even after controlling for confounding factors such as depression, men and women with negative aspects in relationships still had a 25% risk increase. The effect was measurable not only in married couples, but even between close friends.
Job strain occurs in work environments with high psychological demands, especially when workers have little opportunity to make their own decisions. Previous research has determined that chronic job strain is associated with increased risk of a primary cardiac event. A recent prospective cohort study looked at the possibility of a link between a job strain and a recurrent coronary event. Men and women who experienced chronic job strain had a two-fold increase in risk.3 The authors suggested that job strain can activate the sympathetic and renin-angiotensin-aldosterone systems, which may contribute to inflammation of the arterial wall, leading to thrombosis.
It seems that stressful events trigger changes in the neuroendocrine, inflammatory and immunomodulatory systems. While pharmacological approaches may help modulate these effects, there’s no substitute for working from the root of the problems and attempting to eliminate as many everyday stressors as possible. It may not just make for a better life, but a longer one too.
Gregory P. Curnew, MD, FRCPC is Associate Professor at McMaster University in Hamilton, ON, and Director of the Coronary Care Unit at Hamilton General Hospital.
Lilia Tcharnaia is in her 4th year at McMaster University studying biology and psychology.