In the largest study of its kind, military medical researchers have concluded that deployments to war zones and exposure to combat were not major factors behind a significant increase in suicides among military personnel from 2001 to 2008, according to a paper published on Tuesday.

The study, published online by The Journal of the American Medical Association, corroborates what many military medical experts have been saying for years: that the forces underlying the spike in military suicides are similar to those in the civilian world. They include mental illness, substance abuse, and financial and relationship problems.

“The findings from this study are not consistent with the assumption that specific deployment-related characteristics, such as length of deployment, number of deployments, or combat experiences, are directly associated with increased suicide risk,” the authors, based at the Naval Health Research Center in San Diego, wrote. “Instead, the risk factors associated with suicide in this military population are consistent with civilian populations, including male sex and mental disorders.”

But even as it points to nondeployment factors as paramount, the study underscores the complex interplay of war and the mental health of troops, even those who never left the United States. It suggests that the stresses of 12 years of war may have worn on all service members, creating work and travel demands far outstripping those borne by peacetime troops.