Suicide among U.S. troops is often blamed on the stresses of combat, but a group of new studies suggests that factors present before encountering enemy fire may be at least as important.
“It is striking in this regard that the pre-enlistment mental disorders considered here are associated with more than one-third of post-enlistment first-suicide attempts,” said Matthew Nock, Ph.D., a professor of psychology at Harvard University, and colleagues in one of the studies.
Their work is part of the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS), which began in 2008. Three early reports, published March 5 in JAMA Psychiatry, looked at prevalence of suicidal behavior and mental disorders, as well as predictors for suicide among service members.
“These studies contain important new data to help us try to understand how pre- and post-enlistment factors affect suicidal behavior,” said Jitender Sareen, M.D., a professor of psychiatry in the departments of Psychiatry, Psychology, and Community Health Sciences at the University of Manitoba, in an interview. Sareen serves on the scientific advisory board of the Army STARRS project, but is not directly involved in the study.
The suicide rate among U.S. Army regular soldiers rose between 2004 and 2009 regardless of whether they had ever served in an overseas war zone.
Nock’s study was based on a representative cross-sectional survey of 5,428 active-duty Army personnel. The researchers found that 13.9 percent of respondents had a history of suicidal ideation, 5.3 percent had made plans for suicide, and 2.4 percent had made attempts, wrote Nock and colleagues.
Surprisingly, about half of those events occurred prior to enlistment, even though pre-enlistment interviews are supposed to screen out anyone with a history of suicide attempts.
Prevalence estimates of post-enlistment nonfatal suicide attempts were no higher among soldiers than civilians, even though the Army suicide rate rose from 2004 through 2009 to exceed the demographically adjusted civilian rate, said Nock.
Lethality of suicide attempts may be higher among soldiers than civilians because service members more frequently use firearms to kill themselves (61 percent) compared with civilians (50.5 percent), he said. “This possibility highlights the importance of means control as a suicide prevention intervention strategy.”
Of the DSM-IV disorders covered in the study, only major depression and intermittent explosive disorder (IED) were associated (after adjustment) with suicidal behaviors following enlistment.
The association with IED was complex, wrote Nock. Only pre-enlistment IED predicted post-enlistment first suicide attempts, and only post-enlistment IED predicted the transition from ideation to attempts.
IED is an impulse-control disorder, which may have some bearing on suicide, since it is an act that often involves impulsivity and aggression, said Sareen.
“Some suicides are based on impulsivity, and IED may be capturing that risk element the most,” said Robert Ursano, M.D., co-principal investigator of the Army STARRS project and a professor and chair of psychiatry at the Uniformed Services University of the Health Sciences in Bethesda, Md., in an interview. “Similar underlying impulsivity risk may also reflect other disorder risks like substance use or anxiety disorders.”
Contrary to studies of age-matched civilians, pre-enlistment panic disorder and PTSD did not predict post-enlistment first suicide attempts.
“Pre-enlistment histories of PTSD and panic disorder might be markers of resilience among people who enlist in the Army even though they are markers of vulnerability in the general population,” hypothesized Nock.
A second study of seven Department of Defense administrative data systems, focusing on 975,057 Regular Army soldiers, found that being male, less educated, having a lower rank, and being in the service for less than two years elevated risk of suicide death. At the same time, it ruled out one other suspected factor.
During and after the “Surge” in Iraq in 2007-2008, when many more troops were needed, observers suggested that increased suicide rates were due to admitting recruits with waivers for medical, substance abuse, or conduct conditions that would have previously excluded them.
However, the current results “debunk” any such associations, wrote Michael Schoenbaum, Ph.D., a senior advisor for mental health services, epidemiology, and economics in the Office of Science Policy, Planning, and Communications at the National Institute of Mental Health, and colleagues.
That finding reveals significant socio-demographic and Army career correlates of suicide risk, some of which have not been previously documented, said Schoenbaum and colleagues.
A third study, led by Ronald Kessler, Ph.D., a professor of health care policy at Harvard Medical School, examined the 30-day prevalence of DSM-IV mental disorders in the same sample of 5,428 soldiers used by Nock.
About 25.1 percent of respondents recorded any disorder in the prior 30 days, 15.0 percent for any internalizing disorder, and 18.4 percent for any externalizing disorder.
While pre-enlistment rates of internalizing disorders (such as major depression or posttraumatic stress disorder) were lower in the Army group compared with civilian population samples, prevalence of panic disorder and PTSD were higher.
Rates of externalizing disorders (such as intermittent explosive disorder or substance use disorder) before enlistment age for both military and civilian cohorts was about equal, although higher rates of those disorders eventually appeared among the soldiers.
Marriage is usually considered a protective factor versus suicidal behavior, but that was not what Kessler and Nock found. Never-married soldiers had a lower prevalence of mental disorders compared with their married counterparts, noted Kessler, who suggested that the strains of military life on marriages might account for the difference. Nock also found lower odds of suicide attempts among unmarried soldiers, a finding “inconsistent with lower rates of suicidal behaviors among married than unmarried civilians.”
The Army STARRS study is nearing the finish line, said Ursano.
“We have completed data collection,” he said. “New findings and more papers are in the pipeline.”
However, some steps might be taken even now to reduce suicidality, based on current research.
“[T]he Army should develop outreach and treatment programs for new soldiers based on the realization that a nontrivial proportion of its new recruits come into the Army with a history of suicidal behavior or mental disorders that are risk factors for suicidal behaviors,” said Nock.
Besides revising screening procedures to improve assessment of recruits, the Army might create a risk score like those for heart disease, added Sareen. Then, rather than simply reject recruits at higher risk, the Army might direct them to more appropriate tasks within the service, ones that are less stressful than severe combat or require long deployments. ■