By Brenda L. Mooney
ANN ARBOR, MI – New research on short- and long-term cardiovascular risks from traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) could present significant challenges for the VA and the Military Health System.
More than 270,000 servicemembers have been diagnosed with TBI since 2000, according to statistics from the Defense and Veterans Brain Injury Center.
Furthermore, according to the VA’s National Center for PTSD, about 11-20% of veterans of the Iraq and Afghanistan wars have PTSD, in addition to about 10% of those serving in the Gulf War and about 30% of those deployed during the Vietnam War.
A recent study published online by the journal Neurology found that those diagnosed with TBI were 30% more likely to develop a stroke, compared to those who had suffered trauma without brain injury.1
Please click here to participate in this month’s U.S. Medicine readership poll.
“Both stroke and traumatic brain injury are common, costly, and leading causes of severe disability in adults, and approximately 20% of strokes occur in adults under age 65,” said study author James F. Burke, MD, MS, of the Ann Arbor, MI, VA Healthcare System and University of Michigan. “A large proportion of stroke risk is unexplained, especially in the young, so if we can identify new risk factors, we have the potential to prevent more strokes and improve outcomes.”
Another study, posted online by the Journal of the American College of Cardiology and supported by the National Institutes of Health, determined that male twin Vietnam veterans with PTSD were more than twice as likely as those without PTSD to develop heart disease during a 13-year period.2
The study, which was the first long-term research into the association between PTSD and heart disease using objective clinical diagnoses combined with cardiac imaging techniques, “provides further evidence that PTSD may affect physical health,” said Gary H. Gibbons, MD, director of the NIH’s National Heart, Lung, and Blood Institute (NHLBI).
“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.”
Ischemic Stroke Risk
For the stroke study, researchers used records of adults who went to the emergency department or were admitted to a hospital for TBI, or other trauma with no brain injury, during a five-year period in California.
Among 435,630 patients with traumatic brain injury and 736,723 subjects with trauma but no brain injury, 11,229 people, or 1%, had an ischemic stroke over an average of 28 months following the injury. Of those with TBI, however, 1.1% suffered strokes, compared with 0.9% of those with trauma with no brain injury.
After adjusting for stroke risk factors, such as age, high blood pressure and high cholesterol and for severity of trauma, researchers determined that the TBI patients were 30% more likely to develop a stroke than those with trauma but no brain injury.
“While the stroke risk of one person with TBI is small, the overall link between TBI and stroke was substantial — as large as the link between the strongest stroke risk factor, high blood pressure, and stroke,” Burke said. “If further research establishes TBI as a new risk factor for stroke, that would stimulate research to help us understand what causes stroke after TBI and help us learn how to prevent these strokes.”
Study authors pointed out that the TBI-stroke association was of “considerably greater magnitude” in those younger than 50 years old as compared to those older, “suggesting that TBI may be uniquely important in younger patients.”
They also noted that the difference in ischemic stroke risk between the patients with and without TBI was not only related to early high risk.
“The risk of stroke after TBI persisted, even when excluding cases of stroke within 60 days of trauma.”
The report suggested several explanations for the relationship between TBI and stroke, including:
- That alterations in the coagulation cascade caused by TBI, which in turn may increase stroke risk;
- That TBI is also known to cause vascular dissection — a well-described ischemic stroke mechanism; and
- That patients with TBI may accrue conventional vascular risk factors at a faster rate than patients with non-TBI trauma because of a more sedentary lifestyle.
Advantages of Twin Research
For the PTSD study, led by researchers from the Emory University Rollins School of Public Health in Atlanta, heart disease was assessed in 562 middle-age twins — 340 identical and 222 fraternal — from the Vietnam Era Twin Registry. They found that the incidence of heart disease was 22.6% in twins with PTSD, representing 177 individuals, and 8.9% percent in those without PTSD, representing 425 individuals. Heart disease was defined as having a heart attack, having an overnight hospitalization for heart-related symptoms or having undergone a heart procedure.
In addition, positron emission tomography revealed that PTSD patients had almost twice as many areas of reduced blood flow to the heart as individuals without PTSD.
“This study suggests a link between PTSD and cardiovascular health,” said lead researcher Viola Vaccarino, MD, PhD. “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.”
By using twins, both identical and fraternal, researchers were able to control for the influences of genes and environment on the development of heart disease and PTSD. Comparing the 234 twin sets where one brother had PTSD and the other did not, the incidence of heart disease was almost double in those with PTSD compared to those without PTSD — 22.2% vs. 12.8%.
Even after researchers controlled for lifestyle factors such as smoking, physical activity level and drinking, as well as major depression and other psychiatric diagnoses, the effect of PTSD on heart disease remained significant.
In fact, researchers found no link between PTSD and well-documented heart disease risk factors such as a history of hypertension, diabetes or obesity. That suggests the disease might be due to physiologic changes, not lifestyle factors, the authors pointed out.
- Burke JF, Stulc JL, Skolarus LE, Sears ED, et. al. Traumatic brain injury may be an independent risk factor for stroke. Published online before print June 26, 2013, doi: 10.1212/WNL.0b013e318297eecf Neurology 10.1212/WNL.0b013e318297eecf
- Vaccarino V, Goldberg J, Rooks C, Shah AJ, Veledar E, Faber TL, Votaw JR, Forsberg CW, Bremner JD. Posttraumatic Stress Disorder and Incidence of Coronary Heart Disease: A Twin Study. J Am Coll Cardiol. 2013 Jun 26. doi:pii:S0735-1097(13)02506-0. 10.1016/j.jacc.2013.04.085. [Epub ahead of print] PubMed PMID: 23810885.