Combat exposure and mental health: the long-term effects among US Vietnam and Gulf War veterans.

Using a random sample of more than 4000 veterans, we test the effects of combat exposure on mental health. We focus on two cohorts of veterans: those who served in Vietnam (1964-1975) and the Gulf War (1990-1991). Combat exposure differed between these groups in intensity, duration and elapsed time since exposure. We find that combat exposure generally, and exposure to dead, dying, or wounded people, specifically, is a significant predictor of mental health declines as measured by an individual's Mental Component Summary score. Under our general specifications, the negative effects of combat on mental health were larger for Gulf war veterans than for Vietnam veterans as of 2001. These effects persist after controlling for demographic characteristics, insurance coverage, income and assets. Using discrete factor, nonparametric maximum likelihood (DFML) estimation we controlled for unobserved heterogeneity as well as the factors above. In the DFML specifications we find a negative impact of exposure to dead, wounded or dying people for both Gulf and Vietnam veterans, but find no statistically significant effect for combat exposure overall for Vietnam veterans as of 2001. Based on our Gulf war parameters, we estimate that the costs of mental health declines to be between $87 and $318 per year for each soldier with combat service and exposure to dead, dying and wounded people.