Soldiers and veterans seeking treatment for post-traumatic stress disorder should be screened closely for major depression, say the authors of a Canadian study that shows depression is the single greatest driver of suicidal thinking.
The study, reported in this month's issue of The Canadian Journal of Psychiatry, comes as a record number of suicides are taking place among American troops returning from Afghanistan and Iraq, and as the number of suicides reported among Canadian troops last year reached its highest since 1995.
In military veterans diagnosed with post-traumatic stress disorder, about half also experienced symptoms of major depressive disorder at some point in their lives, the authors of the study write.
While looking for indication of serious depression is useful, the researched noted "the task of predicting which people may be at an increased risk of completing suicide is a complex and challenging care issue."
The study involved 193 Canadian Forces veterans, 55 serving military personnel and two RCMP members referred to the Parkwood Hospital Operational Stress Injury Clinic in London, Ont., one of 10 specialized clinics funded by Veterans Affairs Canada to treat veterans with psychiatric illnesses such a post-traumatic stress disorder resulting from military operations.
In addition to post-traumatic stress disorder (PTSD), military personnel and veterans are screened for major depression, anxiety disorders and alcohol abuse. The questionnaire for depression also includes questions about suicidal thinking.
Those in the study had served an average of 15 years and had been sent to a war zone an average of three times. About one-quarter had been sent to Afghanistan at least once.
Most met the criteria for "probable" PTSD, and almost three-quarters screened positive for probable major depression.
Among the total sample, about one-quarter - 23 per cent - reported that they had experienced thoughts of self-harm, or that they would be better off dead, for several days over the previous two weeks.
Another 17 per cent said they experienced those thoughts more than half of the days of the past two weeks; six per cent reported feeling this way nearly every day during the previous two weeks.
Like other studies, the researchers found that PTSD is associated with having suicidal thoughts.
But "what became the biggest predictor was, specifically, depression severity," said Dr. Don Richardson, a consultant psychiatrist at the Operational Stress Injury Clinic and an adjunct professor in the department of psychiatry at Western University in London.
"It really stresses the importance that when you're assessing someone for PTSD it's also critical that you assess specifically for major depression," Richardson said. "From our limited study, it was depression severity that was the most significant predictor of having suicidal ideation."
The concern is that people seeking treatment for military-related trauma might not receive aggressive treatment for depression. The focus instead might be predominantly on PTSD and "exposure therapy" - talking about the traumatic event.
Symptoms of depression include experiencing, on more days than not over the past two weeks, a low mood, less interest in activities people once enjoyed, problems sleeping, changes in appetite, poor concentration, feeling "slowed down" or, the opposite, fidgety or restless, a diminished sense of self-esteem and thoughts of suicide.
According to statistics published in April by the Department of National Defence, 20 soldiers - 19 men and one woman - died of suicide in 2011.
By comparison, 12 soldiers took their lives in 2010, all of them male.
According to DND, suicide rates among serving Canadian Forces personnel are lower than those among the overall Canadian population, and that "there has been no statistically significant change observed in the suicide rates in the CF [Canadian Forces] since 1995."
A year-over-year change, the department adds on a back-grounder on suicide in the CF posted on their website, can be due to "random patterns or indicate the beginning of an upward tend."
Suicide and post-traumatic stress disorder in the military has been under scrutiny at a military police complaints hearing in Ottawa. The hearing, which resumes in September, is examining how the Canadian Forces dealt with the case of Cpl. Stuart Langridge, an Afghanistan veteran who killed himself at CFB Edmonton in 2008.
According to a recent report from the Center for a New American Security, the U.S. army reported a record 33 suicides in July 2011. An estimated 18 U.S. veterans die every day from suicide, the report said.
According to DND, "no consistent relationship has been established between deployment and the risk of suicide."