Soldiers who were deployed to Afghanistan saw their post-traumatic stress disorder (PTSD) reappear five years after returning from the battlefield, a new study has found.

It’s a surprising indication that PTSD symptoms can reemerge after being dormant for a long time, and soldiers may need to be screened for it long after they return home, according to a Reuters report.

Iris Eekhout of VU University Medical Center in Amsterdam, the lead author on the study, said their goal was to get more insight into “the changes in posttraumatic stress complaints in a long-term period after deployment, ultimately to evaluate the timing of an increase in treatment demand after deployment,” she told Reuters.

About 11 to 20 percent of veterans of the Iraq war suffer from some sort of PTSD. PTSD can be a debilitating condition where soldiers experience flashbacks to traumatic events and the constant feeling of fear or shame that can spill over into just about every facet of their lives, making normal, everyday life crippling.

Studies have so far focused on the short-term mental health effects on returning veterans, but there hasn’t been much of an effort to see how it affects veterans in the long term.

A total of 1,007 Duth soldiers who had been to Afghanistan between 2005 and 2008 were examined for the study, with most of them having never experienced a deployment before.

The study found that the average level of PTSD symptoms increased during the first six months after returning home, but then dipped back down to their pre-deployment level after a year.

What was surprising is finding another sudden spike in PTSD symptoms five years after the soldiers had returned — and larger than what had been observed before.