Vietnam War veterans with PTSD are twice more likely to suffer from heart disease than veterans with no history of PTSD, according to a new study.

Data for the study came from 562 middle-aged twins (340 identical and 222 fraternal) enrolled in the Vietnam Era Twin Registry. This is the first time that scientists have been able to establish PTSD to be associated with heart disease in Vietnam War veterans using cardiac imaging techniques. The study was conducted by researchers from Emory University Rollins School of Public Health in Atlanta and their colleagues and was supported by the National Institutes of Health.

Post traumatic stress disorder (PTSD) is a condition that affects a person who has recently witnessed a traumatic event such as a death. About 3.5 percent of the U.S. adult population has been diagnosed with this condition. A recent study had shown that half of all PTSD sufferers also have symptoms of depression.

Soldiers and those exposed to war are at high risk of developing PTSD. In members of military, exposure to brain injuries increase the effects of PTSD, says NIH Medline Plus.

The study was conducted on identical and fraternal twins, which helped researchers control the environment of the study

Experts found that the incidence of heart disease among veterans with PTSD was about 22.6 percent (177 individuals) while it was 8.9 percent in war veterans without PTSD (425 individuals). In a group of 234 brothers where one brother had PTSD, researchers found that the risk of heart disease was double for the one with PTSD than the other (22.2 percent vs. 12.8 percent).

"This study suggests a link between PTSD and cardiovascular health. For example, repeated emotional triggers during everyday life in persons with PTSD could affect the heart by causing frequent increases in blood pressure, heart rate, and heartbeat rhythm abnormalities that in susceptible individuals could lead to a heart attack," Viola Vaccarino, M.D., from Rollins School of Public Health and lead author of the study, according to a press release.

The link between PTSD and heart disease existed even after accounting for other lifestyle factors such as smoking, drinking and poor physical activity levels.

The study is published in the Journal of the American College of Cardiology.