By: Sara G. Miller, Live Science Contributor
Published: 06/29/2015 08:18 PM EDT on LiveScience
Women who experience a traumatic event and develop post-traumatic stress disorder (PTSD) may be at increased risk for heart disease, a new large study suggests.
In the study, researchers found that women who had four or more symptoms of PTSD after a traumatic event had a 60 percent increased risk of cardiovascular disease, such as a heart attack or stroke, than women who experienced no trauma, over a 20-year period.
Women who had experienced traumatic events but who didn't report experiencing symptoms of PTSD had a 45 percent increased risk of cardiovascular disease, the study found.
"PTSD has often been conceptualized or thought of as just a psychological disorder," said Jennifer Sumner, the study's lead author and an epidemiology fellow at Columbia University's Mailman School of Public Health.
"What our findings suggest is that PTSD has effects that go beyond mental health, that also impact physical heath," Sumner told Live Science. [Top 10 Mysteries of the Mind]
PTSD, which affects nearly 8 million Americans yearly, is twice as common in women as it is in men, according to the National Center for PTSD. Symptoms include flashbacks of the trauma, insomnia and emotional numbness.
In the new study, published today (June 29) in the journal Circulation, the researchers collected data from nearly 50,000 women who were enrolled in a long-running study called the Nurses' Health Study II. Every two years for two decades, the participants indicated if they had experienced a heart attack or stroke (and the researchers confirmed these events by reviewing medical records). In the final year of the study, participants were also asked to complete a questionnaire that asked whether they had experienced trauma and PTSD symptoms.
The researchers also determined to what extent the women's health behaviors (such as smoking and lack of activity) and other medical conditions (such as high blood pressure) accounted for the link seen in the study between experiencing trauma and later having heart disease. In women who had experienced trauma and exhibited four or more symptoms of PTSD, the other factors accounted for about half of the association, the researchers found. This suggests that the link between PTSD and heart disease is not just physiological, but that health behaviors also play a substantial role, the researchers said.
"To our knowledge, this is the first study in women to … examine health behaviors and medical risk factors as potential mediators of the associations between trauma exposure, PTSD symptoms and CVD incidence," the researchers wrote.
Still, physiological factors also play a role in the association between PTSD and CVD. For example, research has shown that PTSD is associated with increased levels of inflammation in the body as well as elevations in blood pressure and heart rate,all of which are contributors to cardiovascular disease, said Donald Edmondson, an assistant professor of behavioral medicine at Columbia University, who was not involved with the new study.
It's unclear whether treating women's PTSD could improve their heart health, he said. "The question is, if we were to treat PTSD, will it improve the things that we know go along with PTSD?" Edmondson told Live Science.
The researchers intend to explore how intervention can offset the risk in future studies, Sumner said.
"It will be important to examine whether successful PTSD treatment has a positive impact on cardiovascular health," the researchers wrote.
The new findings suggest "the importance for looking at physical health in women with PTSD and having integrated physical as well as mental health care," Sumner said.
"Right now, the American Heart Association doesn't acknowledge stress or PTSD as an established risk factor for heart disease," said Sumner. "These findings, along with other work in the literature, suggest that it's an important factor to take into consideration," she said.