Historically, American military personnel have a lower suicide rate than their civilian peers (of the same age.) But last year, the pattern was reversed, with troops having a rate of 20.2 suicides per 100,000 troops, versus 19.2 for all civilians of the same age. The main reason for this switch is the large number of troops who have served one or more year-long tours in a combat zone. This leads to PTSD (post-traumatic stress disorder), which is a common cause, or contributor, to suicidal behavior. There were other factors at work as well. For example, a widely used anti-Malaria drug, mefloquine, turned out to cause anxiety and suicidal thoughts if taken by someone with PTSD. Once this was discovered, troops with PTSD symptoms were no longer allowed to use the drug. This impacted a lot of troops, and prevented them from being sent to areas (like the Persian Gulf and Afghanistan) where Malaria is a risk. The number of troops affected is considerable, and caused more troops to do additional combat tours, thus increasing their stress levels.
In 2007, the last year of major combat in Iraq, 10,049 soldiers were diagnosed with PTSD (post-traumatic stress disorder). This was ten times the number diagnosed in 2003 (1,020). The U.S. Marine Corps saw a similar jump, from 206 to 2,114. The stress of repeated trips to combat zones like Iraq and Afghanistan is largely responsible for the sharp jump in PTSD cases, and mental health professionals expected this. There are now better diagnostic tools available, and a lot of publicity for a condition that the troops, and their families, traditionally preferred to keep quiet.
The problem is now, and has always been, pretty serious. Currently, for every soldier killed in combat, at least one is sent back to the United States because of severe PTSD (post-traumatic stress disorder), and several others are treated in the combat zone for less severe cases. During World War II, PTSD was an even more serious problem. In the European Theater, 25 percent of all casualties were serious PTSD cases, compared to about 20 percent today. In the Pacific Theater, the rate varied widely, depending on the campaign. In some of the most intense fighting, like Okinawa in 1945, PTSD accounted for over a third of all wounded. In Iraq, less than ten percent of the wounded are PTSD, but the more troops serve in a combat zone, in combat jobs, the more likely they are to develop PTSD. This has been known for over a century.
The stress of combat, and how to deal with it, has been a hot research topic since World War II. But the war on terror is unique because it is sending more troops into combat, for longer periods, than ever before. As expected, from past experience, the more time troops spend in combat, the more likely they are to suffer from stress.
These days, troops who have been in combat are closely monitored by mental health professionals, more so than at any other time in history. One proven way to help troops avoid PTSD is to allow them to recover, after a combat tour, before going back to the combat zone. There have two different approaches to this. The army lets troops stay at their stateside bases for 18-24 months between 12 month tours. The marines, and the British, allow 12 months at home between six month tours. Because of wartime demands, these recovery (or "dwell") times have been shorter, and this has caused an increase in PTSD casualties.
Research indicates that the six month tours are easier to recover from. With email and easy communications with people in the combat zone, the shorter tours do not waste as much time, getting the lay of the land, as in the past. Units know a year or more that they are going over there, and who they are going to replace. The two units now get in touch months before the relief, and bring the new crew up to date with written reports, pictures and even videos. This preparation is also believed to lessen the development of PTSD.
It's not the prospect of getting killed that causes the stress, but rather the constant state of alertness required to survive in combat. Death is always a factor in military life. Over the last 25 years, the U.S. Army has always lost one or two thousand dead each year to accidents, disease and suicide (in that order). That meant about two troops per thousand died each year. In Iraq, the risk of getting killed in combat is 2-3 percent for a one year tour. For the army overall, the risk of death from combat is less than one percent. But it's the stress that has the long term effects on the most people.