Neurologic deficits may raise risk of post-traumatic stress disorder

[unseennude]

Subtle neurologic deficits appear to be a risk factor for combat-related posttraumatic stress disorder (PTSD), according to a report in the Archives of General Psychiatry for May.

Previous reports have tied such deficits to PTSD, but it was unclear if they were a manifestation of the condition or preceded disease onset, representing a potential vulnerability factor, senior author Dr. Roger K. Pitman, from Massachusetts General Hospital in Boston, and colleagues note.

To sort this out, the researchers tested for mild neurologic deficits or "soft signs" in 25 Vietnam veterans with PTSD, 24 veterans without PTSD, and in combat unexposed identical twins for each group. Forty-five neurologic soft signs (NSS) were evaluated and were rated in severity from 0 (absence) to 3 (most severe).

Combat veterans with PTSD had higher NSS scores than veterans without PTSD, a finding consistent with previous reports. However, the combat unexposed twins of PTSD veterans also had higher NSS scores than the twins of veterans lacking PTSD, suggesting that the neurologic deficits in PTSD patients preceded the onset of their disorder.

Further analysis showed that the higher NSS scores in the twins of PTSD veterans could not be explained by age, noncombat traumatic life events, alcoholism, or comorbid psychiatric disease.

"The results clearly support 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 conclude