Health & Fitness
Research shows that it is not
necessary to experience trauma
directly to be affected by it. A recent
study provides evidence that simply
being around someone who has had a
stressful experience can make changes to
the way the brain processes information.
Post-traumatic stress disorder (PTSD) develops
in some people following a frightening,
dangerous, or shocking event.
Although most people do not develop PTSD after
such an experience, an estimated 7-8 percent of
people in the United States will experience PTSD
during their life.
Symptoms vary from individual to individual, but
can include flashbacks, intrusive negative
thoughts, avoiding places, events, or objects, and
being easily startled.
Even if a specific event does not trigger PTSD at
the time, it raises the chance of an individual
developing it at a later date.
PTSD without experiencing stress
PTSD can be a life-altering condition. However,
the trauma is not limited to the individual who
lived through the traumatic event; it can touch
anyone who interacts with this person. This can
include caregivers, loved ones, or anyone who
witnesses or hears about the others' suffering.
Lead author of the current study, Alexei Morozov
- an assistant professor at the Virginia Tech
Carilion - says:
"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."
In 2008, RAND Corp. - a nonprofit group that
helps guide policy through research and analysis
- assessed a number of studies on PTSD in
previously deployed service members. They
found that people who had not experienced a
serious incident but had heard about it were just
as likely to develop PTSD as those who had
been involved in it. This is referred to as
observational fear.
In earlier studies, Morozov and Wataru Ito - a
research assistant professor at the Virginia Tech
Carilion Research Institute - investigated
observational fear in a rodent model. They found
that animals that witnessed stress in others,
without experiencing any negative events
themselves, displayed an increased fear
response in other situations.
Following on from these findings, the team set
out to investigate any neurological changes that
might underpin the observed behavioral changes.
Specifically, they researched the prefrontal
cortex, which is an area of the brain involved in
understanding the mental state of others and
empathy. Their results are published in this
month's Neuropsychopharmacology.
Brain changes in PTSD mouse model
Researcher Lei Liu measured neural responses in
the brains of mice who had witnessed a stressful
event in another mouse. The experiment involved
placing two mice in adjoining cages. The cages
were separated by a Plexiglass wall with holes
large enough to be able to hear and smell their
neighbor and touch whiskers.
One of the mice (the demonstrator) received 24
electric shocks through the floor of the cage,
one every 10 seconds. The other mouse (the
observer) did not receive shocks. The next day,
the brain of the observer mouse was examined
for changes.
Specifically, the team charted signal
transmission through the inhibitory synapses that
moderate the strength of signals being shipped
to the prefrontal cortex from other brain areas.
The changes measured by the team indicate that
communication is increased via synapses in the
deeper layers of the cerebral cortex, but less so
in more superficial layers. This study
demonstrates that while changes certainly occur,
it is not clear at this stage what the exact
changes are.
As Morozov says: "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."
Although these findings can be considered
preliminary, the hope is that the more we know
about the changes, the more we will be able to
understand how best to treat PTSD.
Originally Posted on http://www.medicalnewstoday.com/
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