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Twin Study Provides More Evidence of Gray Matter, PTSD Link
> 3/19/2008 1:49:52 PM

Doctors have noticed that the brains of individuals with post-traumatic stress disorder (PTSD) have less gray matter than the average brain. While many speculated that stress was destroying neurons, this was not a certain conclusion because genes alone can have dramatic impacts on the volume of brain regions. It was possible that those who eventually get diagnosed with PTSD were genetically predisposed both to respond poorly to stress and to lose brain volume later in life. To settle this matter, Dr. Kiyoto Kasai and his team evaluated the effects of trauma on one member of an identical twin pair. Their results appear in the March issue of Biological Psychiatry.

Dr. Kasai compared the MRIs of Vietnam veterans with PTSD to those of their combat-unexposed twins, finding that the twins with PTSD had reduced gray matter volume in four regions: the pregenual anterior cingulate cortex (a region thought to monitor emotional and sensory conflicts), the right hippocampus, and the left and right insulae. As twins share the same genetic code, and drafted soldiers did not have a choice as to whether they would be deployed (meaning that personality differences can be ruled out), it can now be confidently asserted that stress can cause neural damage and PTSD.

Establishing this chain of causation is important because the military has been dismissing many soldiers without health coverage because of "pre-existing mental conditions." Such claims have some support in the fact that soldiers from the same platoon are often exposed to the same trauma but do not all develop symptoms. While this does demonstrate that some soldiers join with greater vulnerability to mental disorders, Dr. Kasai's study proves that these predispositions would not result in impairment without exposure to extreme stressors. This study will also help dispel the idea of PTSD as just an unhealthy dwelling on the past. Many afflicted with PTSD are haunted by nightmarish memories, but at the base of these memories are experiences that may have led to very real brain damage.

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