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For decades, neuroscientists and physicians have tried to get to the bottom of the age-old mystery of post-traumatic stress disorder, to explain why only some people are vulnerable and why they experience so many symptoms and so much disability.
All experts in the field now agree that PTSD indeed has its roots in very real, physical processes within the brain – and not in some sort of psychological "weakness". But no clear consensus has emerged about what exactly has gone "wrong" in the brain.
In a Perspective article published this week in Neuron , a pair of University of Michigan Medical School professors — who have studied PTSD from many angles for many years — put forth a theory of PTSD that draws from and integrates decades of prior research. They hope to stimulate interest in the theory and invite others in the field to test it.
The bottom line, they say, is that people with PTSD appear to suffer from disrupted context processing. That's a core brain function that allows people and animals to recognize that a particular stimulus may require different responses depending on the context in which it is encountered. It's what allows us to call upon the "right" emotional or physical response to the current encounter.
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A simple example, they write, is recognizing that a mountain lion seen in the zoo does not require a fear or "flight" response, while the same lion unexpectedly encountered in the backyard probably does.
For someone with PTSD, a stimulus associated with the trauma they previously experienced – such as a loud noise or a particular smell — triggers a fear response even when the context is very safe. That's why they react even if the noise came from the front door being slammed, or the smell comes from dinner being accidentally burned on the stove.
Context processing involves a brain region called the hippocampus, and its connections to two other regions called the prefrontal cortex and the amygdala. Research has shown that activity in these brain areas is disrupted in PTSD patients. The U-M team thinks their theory can unify wide-ranging evidence by showing how a disruption in this circuit can interfere with context processing and can explain most of the symptoms and much of the biology of PTSD.
"We hope to put some order to all the information that's been gathered about PTSD from studies of human patients, and of animal models of the condition," says Israel Liberzon, M.D., a professor of psychiatry at U-M and a researcher at the VA Ann Arbor Healthcare System who also treats veterans with PTSD. "We hope to create a testable hypothesis, which isn't as common in mental health research as it should be. If this hypothesis proves true, maybe we can unravel some of the underlying pathophysiological processes, and offer better treatments."
(Score: 2, Interesting) by Ethanol-fueled on Sunday October 16 2016, @12:10AM
I've known sadists in the military who were kept by the military from returning to duty in Iraq because they were known to have enjoyed the battlefield (and the killing). My dad is a Vietnam vet who was shot-at plenty of times in the Vietnamese sticks and, although not a badass, has no PTSD and never showed signs of it. I've had some short-lived PTSD following a few car accidents, which made me afraid to even ride in cars for a good week after the accidents.
One thing I'm wondering, though, is if experiencing early childhood trauma is the root (or at least a very strong correlating factor) of PTSD later in life. You experience or witness something so crazy or violent as a kid that the rug of reality is pulled out from under you and nothing makes sense (there is no context), and oftentimes the mind blocks it out, only for those same symptoms to rear their ugly head later in life when coaxed out by another traumatic situation or trigger. A lot of military personnel are there because, frankly, they were born into less-than-ideal conditions. It would make sense to compare it to a survival instinct kicking in, where any stimulus regardless of context could indicate a danger and there is a heightened sense of awareness. That rustle in your neighborhood tree means nothing, but if I kidnapped you and dropped you in the middle of a jungle, you would likely (if not immedately, after a certain period of time) treat every rustle in a tree as a potential threat to your life. Your brain has defaulted to survival-mode.
Yeah, I went through a psychology phase trying to understand why my momma went nutso.
(Score: -1, Flamebait) by Anonymous Coward on Sunday October 16 2016, @12:18AM
Yeah, I went through a psychology phase trying to understand why my momma went nutso.
It's all your fault; don't you remember how you raped your mother?
(Score: 1) by Ethanol-fueled on Sunday October 16 2016, @12:27AM
If you saw her you'd know that's impossible, unless you have a fetish for Wayne Gretsky.
(Score: -1, Flamebait) by Anonymous Coward on Sunday October 16 2016, @12:43AM
So you don't remember how you raped your mother... I can see we still have much work to do.
(Score: 1) by Myfyr on Sunday October 16 2016, @12:00PM
I recall reading somewhere (can't find it now, unfortunately) that childhood trauma is indeed highly correlated with later PTSD, suggesting increased susceptibility. Which yeah, certainly makes sense.
Also, having a parent with PTSD seems to be a risk factor, due to epigenetic effects (although I imagine there are additional correlations). There is a little information on (possible?) mechanisms for both on wikipedia - https://en.wikipedia.org/wiki/Genetics_of_posttraumatic_stress_disorder#Epigenetics [wikipedia.org]