The study quotes from the journal of a Civil War captain whose personal experiences seem to reinforce this view: "I have always found comforting in battle the companionship of a friend, one in whom you had confidence, one you felt assured would stand by you until the last," Frank Hollinger wrote.
Having a friendly shoulder to cry on at the end of the day also may help dissipate stress hormones, Costa said.
"If you actually see people being killed, your comrade can say, 'No, no. It's all right. It's not your fault.' "
Also unclear is whether veterans from less cohesive units sustained damage that led to stress-related conditions during the war itself or in the years that followed the conflict.
"One theory is that release of hormones in battle may cause systemic inflammation that later in life leads to heart disease and other potentially fatal diseases," Kahn said.
Alternatively, the absence of camaraderie may have made veterans more likely later on to relive battle trauma in the form of post-traumatic stress syndrome.
"Every time a veteran experiences a PTSD reaction, stress hormones are released again," Costa said. "So PTSD leads to repeated exposure to hormones that may over time lead to damaging inflammation."
The latter theory, the researchers admit, is just conjecture. The Pension Bureau did not track PTSD symptoms because the illness was not accepted into diagnostic literature until more than a century later. Neither did the bureau track symptoms that could be ascribed, with the benefit of hindsight, to PTSD. Nonetheless, the researchers view the data as a goldmine.
"Many studies have investigated how social networks combat the effects of stress in people," Costa said. "But they've tended to focus on stress generated in a laboratory setting, where researchers naturally would be prevented from inflicting the high levels
|Contact: Meg Sullivan|
University of California - Los Angeles