When it comes to the effects of emotional stress on the heart, young men and women may not be created equal. Understanding the role of emotional factors—in particular psychological stress—on heart disease risk is a professional passion for longtime NHLBI grantee, Dr. Viola Vaccarino, a leader in women’s health research.
After finishing medical school in Milan, Italy, Viola Vaccarino, M.D., Ph.D., decided she was not interested in pursuing a career in clinical practice or basic science and she came to the United States to study epidemiology. During her doctoral training in epidemiology at Yale University, she learned about the interconnection between psychological factors and physical disease, particularly heart disease, and her interest in the mind-body connection grew.
Currently, Dr. Vaccarino is Professor and Chair of the Department of Epidemiology at the Emory University Rollins School of Public Health. She also holds a joint appointment in the Department of Medicine at Emory.
We recently spoke with Dr. Vaccarino about her latest research on emotional stress and heart disease in young women and her commitment to raising awareness among health care providers about young women’s vulnerability to emotional stress-related heart health outcomes.
Q: What is the current state of the science regarding the relationship between emotional stress and heart disease in women?
There is growing recognition of the importance of emotional stress as a risk factor for heart disease. Compared to men, women have higher levels of psychological risk factors such as early life adversity, post-traumatic stress disorder, and depression. In addition, women are more prone to develop mental problems as a result of stress. Emotional or psychological stress potentially contributes to heart disease in many ways, from influencing heart disease risk factors, to affecting the development of atherosclerosis (hardening of the arteries), to triggering heart attacks. It also may impair the recovery, future health, and quality of life of patients who have already developed the disease.
Emerging evidence suggests that young women are especially vulnerable to the negative effects of stress on the heart, which may result in earlier onset of heart disease or more negative health outcomes if the disease is already present.*
Q: What are the key findings from the Myocardial Infarction and Mental Stress Study (MIMS) related to young women and emotional stress?
The aim of the study was to determine whether it is more common for young women to have myocardial ischemia (reduced blood flow to the heart that can lead to heart attacks) after an emotional stressor compared with men of the same age. Ninety-eight post-heart attack patients (49 women and 49 men) ages 38 to 60 years participated. When exposed to an emotional stressor in the laboratory, women age 50 or younger showed approximately twice the levels of myocardial ischemia compared to men of the same age with similar characteristics. This higher level of what we refer to as mental stress-induced myocardial ischemia continued even after overall health status, heart disease severity, and depression were taken into account. Interestingly, we did not find this gender difference in men and women over age 50. There is something specific about these younger women that makes them particularly vulnerable to emotional/mental stress. This increased vulnerability may result from the fact that these women had a high burden of life stressors and challenging social conditions, such as poverty, depression and history of abuse. Although these conditions did not explain their higher rate of reduced blood flow to the heart, these life stressors may have signaled a higher vulnerability towards emotional stress.
Participants were exposed to an emotional stressor using a standardized mental stress test. First they were placed in a quiet room for 30 minutes to rest. Then they were asked to imagine a stressful life situation, such as a family member being mistreated, and to present the story within three minutes in front of a video camera to an intimidating audience of people wearing white coats. To further increase stress, they were told that their speech would be evaluated by staff. Subsequently, pictures of the heart were taken to examine whether reduced blood flow (ischemia) occurred during mental stress. On a separate day, participants underwent an exercise stress test by walking on a treadmill, and pictures of the heart were taken in a similar way to examine whether there was reduced blood flow with physical stress as a comparison. Compared with age-matched men, women 50 years or younger had twice the rate of mental stress induced myocardial ischemia (52 percent versus 25 percent). Unlike mental stress, we did not see gender differences in ischemia after physical stress tests.
These results are particularly intriguing given that the women tended to have less severe heart disease than men as determined by the degree of blockage in their coronary arteries. We think that abnormal constriction of the coronary arteries, especially the smaller arteries, played a role in mental stress-induced ischemia in these young women rather than coronary blockage. In fact, microvascular dysfunction –constriction of the small blood vessels that lead to the heart— is thought to be more common in women than men, and has been linked to emotional stress and mental stress-induced ischemia.
Ischemia triggered by mental stress has been associated with a doubling of risk for future heart attacks and death in cardiac patients. It could explain why young women (under age 50) who have a heart attack die twice as often as men of the same age despite having less severe heart disease.
Q: What do you see as potential future directions for research into the role of emotional stress in heart disease in women?
Our ultimate goal is to translate this research so that it can be used in clinical practice and prevention. We hope to show that mental stress testing may be a good way to identify those at risk earlier on so that interventions can take place to improve prognosis of heart disease in these patients, or even long before a heart attack ever happens.
Future research needs to focus on younger women and men to better understand the risk pathways that link emotional stress to heart disease risk and allow for prevention before it is too late. In particular, we need to focus more on women under age 50, a group that is rarely studied, so that we can uncover the factors that drive their increased vulnerability to stress. Once we better understand these factors and pathways, we can develop tailored interventions.
“This work is important in helping us gain clues about the processes in the body that contribute to gender differences in health outcomes associated with heart disease,” explained Catherine M. Stoney, Ph.D., program director in the Division of Cardiovascular Sciences at the NIH’s National Heart, Lung, and Blood Institute.
Dr. Vaccarino is the principal investigator for K24 HL077506, and R01 HL109413, and the project PI of P01 HL 101398. The Myocardial Infarction and Mental Stress Study was funded via grant R21 HL093665.
* Depression and history of attempted suicide as risk factors for heart disease mortality in young individuals (Arch Gen Psychiatry, 2011)
*Sex and age differences in the association of depression with obstructive coronary artery disease and adverse cardiovascular events (Journal of the American Heart Association, 2014)