"We were very surprised by the findings," study co-author Cristel Russell said in an American University-published summary. "Most previous research supported the prediction that more traumatic experiences would lead to more negative health outcomes, such as alcohol abuse. We found the opposite - that the most traumatic experiences of killing in combat actually led to a decrease in alcohol abuse post-deployment."
The study, "Changes in Alcohol Use After Traumatic Experiences: The Impact of Combat on Army National Guardsman," was published this month in the journal Drug and Alcohol Dependence by authors from the Walter Reed Army Institute of Research, American University, and the Uniformed Services University.
Members of an Army National Guard Infantry Brigade Combat Team were surveyed on their alcohol use three months before their 2005-2006 combat deployment to Iraq and then three months after their deployment had ended.
The study found that alcohol abuse rates among the soldiers rose from 8.51% before deployment to 19.15% after deployment - more than doubling over that period. Among those soldiers, 15.38% abused alcohol after their deployment but not before.
Those numbers weren't surprising, as past studies have suggested that some percentage of combat veterans will use alcohol to cope with the stress of their experiences.
This study measured six specific combat experiences against future alcohol abuse rates: fighting; killing; threat to oneself; seeing the death or injury of others; witnessing atrocities; and positive experiences.
Soldiers who killed someone during their combat deployment were half as likely to screen positive for alcohol abuse than soldiers who didn't kill someone during their combat deployment. Over the survey period, alcohol abuse actually decreased among soldiers who killed during combat.
The co-authors theorized that "killing experiences may cause soldiers to have an increased sense of mortality and vulnerability that triggers a focus on self-preservation, which manifests itself in reduced high-risk alcohol consumption," the research team reported.
The study included some limitations. It relied on soldiers' judgment and self-reporting and it didn't measure alcohol consumption beyond three months after deployment. Accuracy could also be improved by measuring a larger sample of soldiers and encompassing additional National Guard units based in other regions of the U.S., according to the authors.