Who's at risk for PTSD? VA-DoD research seeks answers
January 5, 2009
Two soldiers go off to war and have similar combat
experiences. One emerges emotionally intact; the other
develops chronic PTSD. Why?
That question is at the core of the Marine Resilience Study. The
San Diego-based project involves VA and Department of Defense
researchers and three and a half battalions of Marines who are
volunteering for the effort.
The researchers are probing dozens of risk factors, from
biological to behavioral, that may lower "resilience"—the ability
to withstand mental and emotional stress. Not everyone with low
resilience will necessarily develop PTSD after a trauma. But the
two issues are closely linked.
One goal is to help the military develop new training methods
or other strategies to boost resilience and prevent PTSD in the first
place. Another is to hone the military's ability to identify early
signs of the disorder and intervene before things worsen.
"The Marines' approach is, you help someone get better. You
don't send them away," says Dewleen Baker MD, research
director of VA's Center of Excellence for Stress and Mental
Health and the study's administrative lead.
Some risk factors may be more suited for
Not every risk factor the researchers identify will be amenable
to change—genetic make-up, for example. Those that are, such as
emotional support or deployment circumstances, are more likely
to be the targets of military intervention. One conceivable
outcome of the study might be new efforts to help troops "garner
and maintain resources for wellness and social connection," says
study co-leader Brett Litz, PhD, of VA's National Center for
PTSD and Massachusetts Veterans Epidemiology Research and
As for biological factors such as heart rate, blood pressure or
chemical signals in the blood, study co-leader William Nash, MD,
a former Navy psychiatrist who deployed to Iraq with the 1st
Marine Division in 2004, says these may be more difficult for
military leaders to directly address. He notes, however: "The
Marine Corps would love for us to find objective, physical
markers for PTSD in our study because that would go a long way
toward reducing the stigma that surrounds PTSD. There are still
too many military service members, including healthcare
professionals, who don't believe PTSD is a real illness resulting
from real injuries to the mind and brain, but instead think it is
caused by a personal weakness. If we can show them biological
markers for PTSD, Marines will better accept that PTSD is no
more their own fault than any other wound of war."
Study includes array of health measures
So far, hundreds of Marines have undergone extensive baseline
testing before shipping out overseas. Many are now back on U.S.
soil and taking part in follow-up tests over six months. In all,
more than 2,000 Marines will take part.
The study is not the first to probe the biological, emotional and
social roots of PTSD. But it is probably the largest and most
detailed project of its kind to date, says Baker.
The researchers are interviewing the Marines in-depth about
issues such as childhood traumas, past alcohol or drug use, marital
situation, spiritual life, deployment and combat experiences,
support within their unit, and past or current PTSD symptoms. On
the physiological side, they are taking cardiovascular measures
and collecting blood, urine and saliva
samples to check the levels of stress
hormones. They will also scan DNA for
gene variants possibly linked to stress and
resilience. In yet other tests, volunteers are
shown different images—some pleasant or
neutral, others showing combat casualties
or other disturbing scenes—while
researchers record eyeblinks and changes
in heart rate. They are also looking at how
the Marines filter out extraneous stimuli
and react to sudden noises.
Most past studies have looked only at a
cross section of combat veterans at a
single point in time and identified traits
more common in those with PTSD—for
instance, a brain region that appears
smaller, or a larger-than-normal heart
response to sudden loud tones. But that
leaves unclear whether the trait is a risk
factor that existed before the PTSD, or a
result of the condition.
Some insights have come from studies
of twins. If a trait is found in combat
veterans with PTSD but not in their
genetically identical brothers, it is
considered a probable result of PTSD, not
an inborn risk factor. But according to
Baker, studies have yielded mixed findings
and more research is needed. By collecting
baseline data and tracking changes over
time, the Marine Resilience Study may
help pin down answers.
Overall, the researchers say they hope
the study will not only build understanding
of why some people develop chronic PTSD
while others don't, but also show how
physical, mental, social and spiritual factors
interact to aid recovery. Nash: "If we can
build better models of recovery, the military
may be able to turn those models into more
effective programs for prevention."
This article originally appeared in the January 2010 issue of VA Research Currents.