Monday, December 24, 2007

Maybe "Another Hole In The Head" Isn't Such a Bad Idea?

The Guardian reports a study of wounded Vietnam vets has found that certain types of head wounds appear to prevent soldiers from developing post traumatic stress disorder.

The unexpected side-effect emerged from a study of nearly 200 former US soldiers in Vietnam, which found that those who had suffered shrapnel injuries to specific regions of the brain did not go on to develop the psychiatric illness.

Jordan Grafman, a senior researcher at the National Institute of Neurological Disorders and Stroke in Maryland, and his team took brain scans of 193 veterans, all of whom had brain injuries from fragments of shrapnel, either from incoming shells or from explosive devices rigged up to booby traps.

They also scanned 52 war veterans who had been in combat but did not suffer any brain injuries.

"Some of our patients could remember events that were very traumatic, such as attacking villages and seeing comrades dying, but it didn't seem to affect them in the same way," said Grafman, whose study was published in Nature Neuroscience yesterday.

Following the brain scans the veterans were divided into two groups, depending on whether they had a history of PTSD or not. When they looked at the distribution of brain injuries among the two groups the doctors realised that troops with damage to one of two parts of the brain were extremely unlikely to have PTSD.

One of the brain regions involved was identified as the amygdala, an almond-sized bundle of neurons in the seat of the brain that is important for interpreting fear and anxiety.
The second region is known as the ventromedial prefrontal cortex, or vmPFC, a larger structure found nearer the front of the brain, which is also thought to be involved in processing fear.

...none of the 50 men who suffered damage to the amygdala had ever experienced PTSD. Those who sustained a shrapnel wound to the vmPFC were also less likely to have PTSD, with 18% affected. In comparison, some 48% of those with no brain injuries and 40% of men with any other kind of brain injury had been diagnosed with PTSD.

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