Post-traumatic stress disorder, also called PTSD, is an anxiety
disorder that can develop in some people after they experience a
shocking, scary, or dangerous event, suggests the National Institute
of Mental Health.
Most people who live through dangerous events do not develop the
disorder, but about seven or eight out of every 100 people will experience
post-traumatic stress disorder at some point in their lives, according
to the U.S. Department of Veterans Affairs' National Center for PTSD.
‘People who heard about a serious incident - such as a gunfire exchange - were just as likely to develop post-traumatic stress disorder as the people who actually lived through the incident.’
PTSD doesn't stop at direct victims of illness, injury, or a
terrorist attack; it can also affect their loved ones, caregivers, even
bystanders - the people who witness or learn about others' suffering.
Negative emotional experience leaves a trace in the brain, which makes us more vulnerable. Scientists at the Virginia Tech Carilion Research Institute have
discovered that observing fear in others may change how information
flows in the brain.
The results of their study were scheduled for advance online publication today in Neuropsychopharmacology
, the official publication of the American College of Neuropsychopharmacology.
an assistant professor at the Virginia Tech Carilion Research Institute
and lead author of the study, said, "Traumatic experiences, even those
without physical pain, are a risk factor for mental disorders."
Morozov, who is also a faculty member in the Department of
Biomedical Engineering and Mechanics in Virginia Tech's College of
Engineering, also noted that while a traumatic event may not immediately lead
to the disorder, it increases odds of developing the disorder.
"There's evidence that children who watched media coverage of the
September 11 terrorist attacks are more likely to develop PTSD later in life
when subjected to another adverse event," Morozov said.
According to a 2008 RAND Corp. assessment of multiple studies of
post-traumatic stress and depression in previously deployed service
members, people who heard about a serious incident - such as a gunfire
exchange - were just as likely to develop post-traumatic stress disorder
as the people who actually lived through the incident.
In previous studies, Morozov with Wataru Ito, a research assistant
professor at the Virginia Tech Carilion Research Institute, found that
rodents who witnessed stress in their counterparts but did not
experience it firsthand formed stronger than normal memories of their
own fear experiences - a behavioral trait relevant to some humans who
experience traumatic stress.
Based on these findings, the researchers investigated whether the
part of the brain responsible for empathizing and understanding the
mental state of others, called the prefrontal cortex, physically changes
after witnessing fear in another.
Lei Liu, a postdoctoral researcher in the lab, measured transmission
through inhibitory synapses that regulate strength of the signals
arriving in the prefrontal cortex from other parts of the brain in mice
who had witnessed a stressful event in another mouse.
"Liu's measures suggest that observational fear physically
redistributes the flow of information," Morozov said. "And this
redistribution is achieved by stress, not just observed, but
communicated through social cues, such as body language, sound, and
According to Morozov, this shift may potentially enable more
communications via the synapses in the deep cellular layers of the
cerebral cortex, but less so in the superficial ones. It's not yet clear
exactly how the circuits have altered, only that they have indeed
"That's the next step," Morozov said. "Once we understand the
mechanism of this change in the brain in the person who has these
experiences, we could potentially know how something like post-traumatic
stress disorder is caused."