As someone who has suffered a severe concussion (and several less severe ones) I'm fascinated by the whole field of Traumatic Brain Injury (TBI) and what it can lead to... Especially since I may become a victim at some point in time.
Here's a great summary of a study that is helping scientists understand the links between TBI and PTSD. This is a pretty common situation in soldiers that were in Iraq and Afghanistan.
Philadelphia, PA, February 22, 2012 – Mild traumatic brain injury (TBI) and posttraumatic stress
disorder (PTSD) are cardinal injuries associated with combat stress, and TBI increases the risk of
PTSD development. The reasons for this correlation have been unknown, in part because physical
traumas often occur in highly emotional situations.
However, scientists at University of California at Los Angeles provide new evidence from an animal
model of a mechanistic link underlying the association between TBI and PTSD-like conditions.
Using procedures to separate the physical and emotional traumas, Dr. Maxine Reger and colleagues
trained rats using fear conditioning techniques two days after the rats had a concussive brain trauma.
This ensured the brain injury and experience of fear occurred on different days.
Dr. Michael Fanselow explained their findings: “We found that the rats with the earlier TBI acquired
more fear than control rats (those without TBI). Something about the brain injury rendered them more
susceptible to acquiring an inappropriately strong fear. It was as if the injury primed the brain for
learning to be afraid.”
To further understand why this happened, the researchers analyzed a small piece of brain tissue, the
amygdala, which is the brain's critical hub for fear learning. They found that there were significantly
more receptors for excitatory neurotransmitters that promote learning. “This suggests that brain injury
leaves the amygdala in a more excitable state that readies it for acquiring potent fear,” added
Fanselow.
These findings now suggest a causal link between TBI and the increased susceptibility to PTSD, and
identified an important role for the amygdala in this effect. “The next challenge is to characterize the
neural circuitry and neurobiology of this effect. These are critical steps in building from these findings
to preventative or therapeutic advances,” commented Dr. John Krystal, editor of Biological Psychiatry.
Although this work was performed in rats, these findings also suggest that people who suffer even a
mild traumatic brain injury are more likely to develop an anxiety disorder, and that proper management
of stress after such an injury could be critically important to maintaining ones’ mental health.
The article is “Concussive Brain Injury Enhances Fear Learning and Excitatory Processes in the
Amygdala” by Maxine L. Reger, Andrew M. Poulos, Floyd Buen, Christopher C. Giza, David A. Hovda,
and Michael S. Fanselow (doi:10.1016/j.biopsych.2011.11.007). The article appears in Biological
Psychiatry, Volume 71, Issue 4 (February 15, 2012), published by Elsevier
Tuesday, September 27, 2016
A New Link between Traumatic Brain Injury and Posttraumatic Stress Disorder
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