Neurologic Soft Signs Mark Vulnerability to PTSD

Twin study shows neurologic dysfunction associated with combat-related post-traumatic stress disorder runs in families

WEDNESDAY, May 3 (HealthDay News) -- A study of identical twins suggests that subtle neurologic dysfunction associated with combat-related post-traumatic stress disorder (PTSD) is not acquired with the trauma but rather represents an antecedent familial vulnerability factor for PTSD, according to a report in the May issue of the Archives of General Psychiatry.

Tamara V. Gurvits, M.D., Ph.D., of the Veterans Affairs Medical Center in Manchester, N.H., and colleagues examined 49 male combat-exposed Vietnam veterans, 25 of whom had PTSD, and their non-combat-exposed monozygotic twins for neurologic soft signs (NSS). Tests for NSS included drawing tests, reciting tongue-twisters and walking on tip-toe.

The investigators found that vets with PTSD had higher NSS scores than those without PTSD, indicating poorer neurologic function. NSS scores were also higher in their non-combat-exposed twin compared with twins of vets without PTSD. The results were not affected by age, number of traumatic events experienced, alcoholism or anxiety disorders.

The authors indicate that the higher NSS scores in PTSD vets and their twins represent dysfunction in the cerebral cortex, a region responsible for dealing with fear response after trauma, which could increase the risk of developing PTSD. Conversely, this suggests "a healthy nervous system may, for all the previously mentioned reasons, confer resilience in the face of highly stressful life events," they write.

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