Magazine article Clinical Psychiatry News

Hippocampal Volume Just One Factor in PTSD. (Vietnam Twin Registry)

Magazine article Clinical Psychiatry News

Hippocampal Volume Just One Factor in PTSD. (Vietnam Twin Registry)

Article excerpt

BALTIMORE -- The question of whether smaller hippocampal volume is the cause or result of posttraumatic stress disorder was answered at least preliminarily by data presented by two speakers at the annual meeting of the International Society for Traumatic Stress Studies.

Dr. J. Douglas Bremner reported data on 26 pairs of dizygotic twin brothers. One twin in each pair had been in combat in Vietnam and developed resulting posttraumatic stress disorder (PTSD); the other twin had been in the military, had not served in Vietnam, and did not have PTSD.

Magnetic resonance imaging showed that the right hippocampal volume of the PTSD twins averaged 9% less than that of their unaffected brothers. Verbal memory function was significantly impaired only in the brothers with PTSD.

"These preliminary findings are consistent with stress underlying these changes," Dr. Bremner said.

The original goal for the ongoing study was to enroll 60 pairs of combat-discordant twins: 30 dizygotic and 30 monozygotic pairs.

However, the current 26 pairs of dizygotic and 15 pairs of monozygotic twins "are about all that we are going to get, said Dr. Bremner, of the departments of psychiatry and radiology at Emory University, Atlanta.

The data on the 15 sets of monozygotic twins enrolled in the trial have not been analyzed.

Like the twins in the study described by Dr. Bremner, those in the study presented by Mark Gilbertson, Ph.D., were included in the Department of Defense's Vietnam Era Twin Registry. The collection of data on more than 7,000 twin pairs is housed in Seattle.

All the registered twins were born between 1939 and 1957 with a median birth year of 1949. …

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