Unique Activation Pattern of PTSD Detected
> 7/30/2007 2:09:00 PM

Traumatic childhood experiences often haunt victims into adulthood. Some scientists have posited that these damaging memories cannot be easily forgotten because they actually change the functioning of the brain. This is supported by a study we reported on earlier by Dr. Victor Carrion, who found that children with PTSD developed smaller hippocampuses later in life. The fact that there was no detectable size difference in childhood suggests that those diagnosed with PTSD had their development stunted rather than just being predisposed to poorly handle stress.

Dr. Carrion received a grant from the NIH to further explore the brain changes caused by PTSD. For this new study, he used functional magnetic imaging to show that there was not only a structural difference but also a processing difference. 30 youths were scanned as they performed a Go/No-Go task that required them to consciously repress a response whenever the category was not appropriate. While the PTSD and the control  group received similar scores for speed and accuracy, different regions of the brain had the strongest activation. Control subjects exhibited more middle frontal cortex activation  while PTSD subjects showed more medial frontal activation. Dr. Ridderinkhof has linked the medial frontal area to the process of monitoring ongoing actions and then later modifying behavior, one of the many functions also performed by the frontal cortex. While these two areas can perform similar functions, there may be a significant difference in the long term consequences and subjective experience of relying on one or the other.

This activation difference is a valuable discovery because it may allow doctors to diagnose PTSD even when there is no noticeable decline in test scores. It may be possible to detect a change in processing before irreversible structural changes like a shrunken hippocampus become apparent. Dr. Carrion found an additional activation difference that might open the door to even more specific diagnoses. He found that PTSD subjects who engaged in self-injurious behavior had greater insula and orbitofrontal activation. Earlier intervention, or at least more careful monitoring, are now possible for children at risk for self-injury.

These findings sheds some light on the way that traumatic events become not just bad memories but catalysts for large changes in the way that the mind works. This falls into place with an article of ours last week about the way that trauma changes the body and causes chronic health problems. Perhaps these changes can serve as advantageous adaptations to prepare us for further trauma, but when the mind stays on high-alert for too long without any real threats to protect us from, this adaptation can turn into a disability.

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