Brian Van Reet is a former sergeant in the Army who served in Baghdad from 2004 to 2005.

It has become an all-too-common story: A young person joins the military, deploys to war and later returns home, only to be troubled by the horrors of combat duty. This traumatic past intrudes on the soldier’s new life, tormenting him or her up to the point of substance abuse, criminality and even suicide.

This narrative of combat trauma and self-destruction has gained primacy, partly because it is easy to understand — it sounds true — and partly because it sometimes is true. It elegantly explains how acts of violence, directed inwardly and outwardly, resonate through time.

Science, however, is beginning to suggest that the link between war, post-traumatic stress disorder (PTSD) and self-harm is not what many expect, given our prevailing cultural narratives.

For instance, a study published this month in the Journal of the American Medical Association (JAMA) concludes that exposure to combat does not increase the likelihood that a service member will take his or her own life.

These counterintuitive findings demonstrate the need for further examination of war’s effects on those who fight it. As we attempt to understand this problem, it might be helpful to distinguish the experience of fighting a war from the experience of serving in the military during wartime.

The looming threat of year-on, year-off deployments places a psychological burden on all service members — regardless of whether one is ever deployed — and may encourage risk-taking behavior or a live-for-the-day mentality that develops in response to a highly uncertain future.

Compounding this phenomenon, young people who seek danger are perhaps more likely to join the military in times of war than in peacetime. People with a genetic predisposition to thrill-seekingmight also be more likely to drink, to use drugs, to suffer financial ruin, to get divorced — in short, to act in ways that have been shown to correlate strongly with suicide.

In thinking about this problem, ­combat-related trauma should be a factor, but so should the character of military recruits before they see action. Other considerations are the structural character of the military, which is capable of rendering draconian shades of misery at a strength, if not intensity, that rivals the better-documented horrors of the battlefield.

In 2003, I received stop-loss orders. They meant that instead of getting out of the Army after two years, as I had expected, I would instead be deployed to Iraq. Eighteen months later, when the stop-loss order was finally lifted, I had spent almost twice as much time on active duty as I had signed up for.

After I was discharged, I remained a member of the Individual Ready Reserve but thought I was finished with the Army. Then one day, years later, I received a letter ordering me to report for “muster duty” at a mobilization center. There, after considering whether I wanted to chance being called back to active duty, I signed an addendum to my enlistment contract that obligated me to attend weekend drill once a month but that also guaranteed I could not be deployed for the remainder of my time in service.

Combat brings its own long-lasting privations — most notably to the civilians who live in places where wars are fought — but the institution of the Army caused me as much sustained mental hardship as any traumatic thing I saw or did while fighting overseas.

I know I am lucky to be able to make that statement. I am also lucky that even when I went through hard times, I always thought I had something to live for. I never considered suicide as a feasible escape.

But if I had taken my own life, many people would have assumed I did so because something I had seen or done in Baghdad haunted me. In the unlikely event that my death made the news, the media probably would have been quick to mention my tour in Iraq but less ready to speculate on whether I drank too much or suffered from a mental disorder such as manic depression. Yet the latter two factors have been shown, including in the recent JAMA study, to correlate more strongly with military suicide than does a person’s status as a combat veteran.

Many are quick to retell the combat trauma narrative as a way to explain why veterans hurt themselves. It is the stuff of Greek tragedy, the sins and wounds of the past revisiting the present, and it makes for a better, more dramatic story. It has the ring of truth, but that does not always — or even commonly — make it true. PTSD is a valuable concept but not if it is used as a catchall for the myriad ways that war, peace, genetics and institutions all shape the behavior of veterans.