Combat has little influence on health problems in Vietnam vets

Investigators at the Veterans' Affairs Medical Center and the School of Medicine have found that the psychological trauma of combat had little effect on the physical health of Vietnam veterans 20 years after their experience in Southeast Asia.

Studying more than 4,700 pairs of identical and fraternal twin brothers who served during the Vietnam War, the researchers found that combat played only a minor role in health problems such as hypertension, respiratory difficulty and gastrointestinal disorders. The findings, reported in the Sept. 23 issue of Psychosomatic Medicine, show that inherited factors and environmental experiences not related to combat explain more than 90 percent of reported health problems.

Eisen: Veterans researcher

Past studies that have suggested an association between combat and physical health lacked adequate control groups, according to principal investigator Seth A. Eisen, M.D., associate professor of medicine and staff physician for the Department of Veterans' Affairs. He pointed out that while it is relatively easy to find subjects exposed to substantial psychological stress from combat, it is difficult to find an appropriate control group -- individuals who are very similar yet lack combat exposure.

"Everything about the characteristics of people is explained by some combination of inherited factors and environmental experiences," Eisen explained. "Twins provide a wonderful way to better understand this because if we find differences between twin siblings, those differences must be due to influences from outside of the family."

The research team, which included colleagues at the University of Illinois, Saint Louis University, Boston University and Harvard Medical School, gathered data from identical and fraternal twins in 1987 by mail or telephone, using a 30-page questionnaire. The veterans who were identical twins had exactly the same genes, and those who were fraternal twins shared about half of their genes. The veterans' mean age at the time of the study was 38, and they had an average of 19 years of military service.

The investigators found that, for the entire group of twins, inherited factors explained about 54 percent of the reports of hypertension, while combat exposure explained less than one percent. For joint disorders such as arthritis, genetics accounted for 37 percent of the incidence in twins, while combat exposure explained only 2.6 percent. Combat veterans did report greater hearing loss and skin problems. In all, combat experiences explained no more than 10 percent of current health problems in Vietnam vets.

Eisen suggests a follow-up study be done because the emotional distress caused by combat may take years to become evident in veterans' psychological and physical health.