Certain Brain Injuries May Prevent PTSD
> 12/31/2007 4:18:02 PM

Combat experience has long been accepted as one of Post TraumaticStress Disorder's predictors, and direct damage to the brain is one ofthe most traumatic injuries sustained during battle. Researchers havenoted the changes inbrain activity associated with the condition, and most namethe disorder as a common side-effect of all neurological injuries. Buta majorclinical discovery now contradicts that general impression:while physical trauma serves as one of the disorder's major causes,invasive damage to certain areas of the brain may actually prevent itsdevelopment.

General medical consensus through thelate 20th century held that states of unconsciousness and near-amnesiacaused by severe brain injuries often "precludes encoding of the traumaticexperience," but researchover the last decade has very conclusively linked braindamage to PTSD, with more than 1 in 4 victims of traumatic brain injurydisplaying symptoms severe enough to warrant positive diagnoses 6months after sustaining said damage. And while post-traumatic amnesiawas common among the sample, its influence only persisted, on average,for 37 days. This finding is very much in keeping with the standardPTSD model in which symptoms often follow a period of seeming normalcyafter which the mind begins to exhibit the full effects of the eventsit has endured.

The 25% prevalence of PTSD amongthe injured is approximately the same as that observed in veterans oftraumatic combat and those who sustain other bodily damage, leading tothe conclusion that brain injury very commonly precedes PTSD and thatvictims of such trauma should be carefully observed in order toidentify potential markers for the disorder. Interestingly, PTSDpresents in different forms among this sample: invasive memories of theincident in question are far less common for them than for victims ofaccidents, assaults and terrorist attacks. The "reliving the trauma"phenomenon may be precluded by emotional and physiologicalreactivity/sensitivity, which is extremely common among victims ofbrain injury. It would seem that the brain's function is oftencompromised, leading back to the study's primary conclusion: damage tothe brain may alter neurological patterns in a way that significantlyreduces the likelihood of a patient developing PTSD if the injuriesoccur in areas responsible for the disorder's most common side-effects.

The most recent study, which compared PTSD levelsin a sample of Vietnam veterans, is the first to recognize thatpreventive relationship and name the particular brain regions mostlikely to facilitate it. The study focused on veterans who'd registeredfor the VietnamHead Injury Study; due to their considerable number and PTSDrates as high as 30%, these former soldiers very often make up astandard sample group for such experiments. The findings that mostsurprised researchers were those regarding soldiers who'd sustainedinvasive damage to two areas: the amygdala, which controls emotionalarousal and fear-based auto-responses, and the ventromedial section ofthe prefrontal cortex, which is believed to play a role in regulatingfear and risk assessment. Where 40% of patients with injuries to otherparts of the brain displayed clear evidence of PTSD, only 18% of thosewith damaged amygdalas or vmPFCs were affected. Researchers suspectthat abnormalities in these two regions will also be apparent in PTSDvictims whose conditions stem from events unrelated to militaryexperience.

One of the most disturbing aspects ofthe study was the fact that so many of the subjects still suffered fromPTSD almost 40 years after the war. The American military is,fortunately, sensitive to the various incarnations of this phenomenon;they seem to have beat this study to the punch by developing aneducation program specifically designed to heighten recentveterans' awareness of PTSD cases caused by damage to the brain.Effectively treating patients moments, hours or even days aftertraumatic incidents occur is nearly impossible in a war zone, and thefact that damages to relevant parts of the brain occurred as animmediate result of the battlefield injuries may complicate the searchfor effective PTSD treatments. But this newfound knowledge could leadto future forms of therapy that are able to stimulate these areas inorder to temper the more severe symptoms of the disorder. Researcherssuggest that deep brain stimulation, used to counter Parkinson'sdisease by altering electrical activity in certain areas of the brain,could prove useful if aimed at the regions in question. Concussivedamage to the brain due to homemade explosives is far more common amongveterans of our current overseas conflicts than the invasive injuriesexamined here, but the issue remains, and this revelation couldeventually help prevent or moderate the development of PTSD in injuredveterans. Sparing some of them from the often debilitating effects ofthe condition is a worthy goal no matter how much funding and researchit requires.

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