According to lead researcher Viola Vaccarino, MD, PhD, the study aimed to clarify the relationship between PTSD and coronary heart disease in a group of middle-aged male twins from the Vietnam Era Twin Registry. Participants included twin pairs without self-reported coronary heart disease at the beginning of the study. The pairs included twins where at least one brother had a history of PTSD or major depression, and twins without either condition of PTSD or major depression. Participants were followed for about 13 years.
“Our study is the first one to link PTSD to coronary heart disease using objective measures of heart disease, such as cardiac imaging techniques and clinical histories,” explains Vaccarino, professor and chair of the Department of Epidemiology and the Wilton Looney Chair of Cardiovascular Research. “Using a twin design and both clinical and imaging endpoints, we were able to clarify inconsistent results found in previous research.”
The findings appear online today in the Journal of the American College of Cardiology and in the September 10 print issue.
Of nearly 562 twins (281 pairs) with an average age of 42 years at the beginning of the study, the incidence of coronary heart disease was more than double in twins with PTSD than in those without PTSD. In addition to a clinical history, the researchers used positron emission tomography, a nuclear imaging scan that identifies areas of reduced blood flow to the heart due to coronary heart disease. The nuclear scans of twins with PTSD showed about twice as many areas of reduced blood flow to the heart than those of twins without PTSD. Results were similar when comparing twins with PTSD to their brothers who did not have PTSD.
“This study provides further evidence that PTSD may affect physical health,” said Gary H. Gibbons, M.D., director of the NIH’s National Heart, Lung, and Blood Institute (NHLBI), which partially funded the study. “Future research to clarify the mechanisms underlying the link between PTSD and heart disease in Vietnam veterans and other groups will help to guide the development of effective prevention and treatment strategies for people with these serious conditions.”
Underlying mechanisms that link PTSD and coronary heart disease have yet to be clarified; however, changes in the central and autonomic nervous system involved in the regulation of the heart are suspected to play a role. For example, individuals with PTSD tend to show periodic increases in blood pressure and heart rate after exposure to traumatic reminders. These repeated responses in everyday life may eventually affect cardiovascular health in a cumulative fashion.
“One surprising finding was that the increased risk that we saw in veterans with PTSD was not due to ‘conventional’ coronary heart disease risk factors, such as obesity or blood lipids” says Vaccarino. “The increase also was not explained by adverse health behaviors such as smoking and physical inactivity. This information will aid in future research that addresses the underlying mechanisms of increased cardiovascular risks in those with PTSD.”
The study was supported by The National Heart, Lung, and Blood Institute grants K24HL077506, R01 HL68630, and R21HL093665-01A1S, the National Institute of Aging grant R01 AG026255, the National Institute of Mental Health under award number K24 MH076955, and by the American Heart Association. Support also was provided by the National Center for Advancing Translational Sciences under award number UL1TR000454 and the National Center for Research Resources grant MO1-RR00039.