The study finds that a significant minority of US ex-military personnel has suicidal thoughts.
The research, published in the Journal of Affective Disorders, used data from a nationally representative sample of over 2,000 American vets who were surveyed twice - once in 2011 and again in 2013 - in a study led by the Veteran's Affairs (VA) National Center for PTSD.
Each time, the survey asked the veterans whether they had experienced suicidal thoughts in the past 2 weeks, and also about a host of other factors associated with suicidal thinking.
The results showed that around 86% of participants reported having no suicidal thoughts in the previous 2 weeks at both times they were surveyed.
However, within the 14% or so who did report having had suicidal thoughts on at least one of the two survey occasions, nearly 4% showed remitted suicidal thinking - that is, they reported having thought about suicide in 2011, but not in 2013. And 5% showed the opposite pattern - they reported having thought about suicide in 2013, but had not done so 2 years earlier.
The researchers say this result highlights how suicidal thinking can come and go, at least within the span of a couple of years. This contradicts previous studies that suggest suicidal thinking tends to be a longer-term problem and emphasizes the need for continual monitoring of symptoms.
The findings also reveal a need for more outreach support. Among participants who reported having thought about suicide in 2013, but not 2 years earlier, only 35% had ever received any mental health treatment.
Social connectedness can be a buffer against suicide
Not surprisingly, the results show higher levels of physical health problems, psychiatric distress and history of substance use were linked to chronic suicidal thinking.
The findings also support the idea that social connectedness can be a buffer against suicide risk. It emerged as a factor in the 4% who showed remitted suicidal thinking, and among veterans who showed less social support in 2011, more were likely to report suicidal thoughts in 2013.
However, the authors note that for many of the participants reporting chronic suicidal thinking, social support appeared to have little effect. For these veterans, the priority is likely to be psychiatric and physical health care, as well as help dealing with substance abuse.
The researchers explain it is not easy to compare their figures with rates of suicidal thinking in the general population because studies on suicide vary widely in their methods.
However, a study that it might be reasonable to compare with, is one from the Centers for Disease Control and Prevention (CDC) that found 3.7% of adults in the US report having thought about suicide in the previous 12 months. By that standard, the rate of suicidal thinking in veterans is high.
This fits with other estimates that show while only 13% of adults in the US are veterans, they account for 22% of suicides, and that veterans are twice as likely to die from suicide as civilians.
The authors acknowledge that 2 years is probably not long enough for this kind of study - it cannot draw conclusions about the longer term.
Another potential weakness of the analysis is that around a third of the participants who responded in 2011 did not take part in 2013. If those who dropped out were the ones more likely to have suicidal thoughts, this could mean the estimates about suicidal thinking in veterans are too low.
Nevertheless, the researchers say their findings suggest "a significant minority" of veterans in the US has chronic, onset or remitted suicide ideation (SI), and conclude:
"Prevention and treatment efforts designed to mitigate psychiatric and physical health difficulties, and bolster social connectedness and protective psychosocial characteristics may help mitigate risk for SI."
In July 2015, Medical News Today learned that even 40 years after the end of the war, around a quarter of a million Vietnam veterans have PTSD or some other form of mental ill health.