Neurologic dysfunction, cued by 'soft signs,' may predate PTSD.
The results of their twin study indicate that, instead of originating from the trauma, this neurologic dysfunction predates posttraumatic stress disorder (PTSD) and likely predisposes patients to it.
The researchers studied 49 pairs of identical male twins in which one twin had been exposed to combat during the Vietnam War and the other had not.
In 25 pairs, the combat-exposed twin had current PTSD, while in the remaining 24 pairs, the combat-exposed twin had never had PTSD.
The subjects were assessed for 45 possible "soft signs" that indicated subtle neurologic dysfunction. These included difficulty in copying simple figure drawings; an impaired sense of direction; and excessive difficulty in mirroring movements, walking on tiptoe or heel, repeating a tongue twister, or performing simple finger- or foot-tapping tasks.
Combat veterans with PTSD had significantly higher scores on the assessments of neurologic soft signs than did combat veterans without PTSD. This confirms previous reports that subtle neurologic compromise is manifested as an increase in neurologic soft signs in people with combat-related PTSD, Dr. Gurvits and her associates said (Arch. Gen. Psychiatry 2006:63:571-6).
Surprisingly, however, unexposed identical twins of PTSD patients also had significantly higher scores on the assessments of neurologic soft signs than did the unexposed twins of veterans who didn't have PTSD. This difference was not related to possible confounding factors such as history of potentially traumatic noncombat lifetime events, alcoholism, psychiatric comorbidity, or drug use.
This finding "clearly support[s] the conclusion that subtle neurologic dysfunction in PTSD does not reflect brain damage acquired along with the PTSD but instead represents a familial vulnerability factor, which likely antedates the traumatic exposure," the investigators said.
The researchers cautioned that their results with this patient population may not be generalizable to victims of noncombat traumatic events or to women, and recommended that twin or prospective studies be conducted to examine the issue in these groups.
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|Title Annotation:||posttraumatic stress disorder|
|Author:||Moon, Mary Ann|
|Publication:||Clinical Psychiatry News|
|Date:||Jun 1, 2006|
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