Professor Dorthe Berntsen of the Center on Autobiographical Memory Research at the Aarhus University in Denmark, military psychologists at the Danish Center for Defense Veterans and researchers from Duke University in North Carolina surveyed 746 Danish soldiers who served in Afghanistan. The soldiers completed a questionnaire five times -- before their posting, during their time in Afghanistan and three times after their return to Denmark.
The study, published in the journal Psychological Science, found many of the soldiers had already experienced trauma before they went to Afghanistan, and that affected the way they reacted during their posting.
A small proportion of the soldiers said they felt better as a result of their posting, but they had a high level of PSTD before their tour of duty, which decreased during or immediately after their posting to Afghanistan, after which it rose again.
"Being sent abroad in the military services can be an attractive opportunity for this group of young people to escape from their everyday lives in Denmark," Berntsen said in a statement.
The largest proportion of soldiers were a resistant group and were not affected by their everyday situation either before their posting, during their tour in Afghanistan or after returning home.
About 5 percent of the soldiers did not experience trauma before the war but their mental state deteriorated while they were there, and did not recover after they returned home, Berntsen said.