"When we study Iraqi citizens who have fled to the US ... PTSD is common," said Bengt Arnetz, co-author of the study conducted by Uppsala University in Sweden, Wayne State University in Michigan and the University of Baghdad.
However, among soldiers and civilians who stayed in Iraq, "neither of these groups showed any signs of post-traumatic stress 10 years after that war," he said.
"Once you've fled a country at war, you're no longer just focused on survival and you start to realise what you've been through. In addition, you have to start building up a life from nothing," he told AFP.
Arnetz said Iraqis who stayed in Iraq "still live in a situation of stress and we think that can explain why they hadn't developed PTSD" after 10 years.
The study, published in the New Iraqi Journal of Medicine, was conducted in 2001, 10 years after the end of the first Gulf War and before the start of the US-led war on Iraq in 2003.
More than 1,100 Iraqi males in the US and Iraq were surveyed for the study, comprising 742 soldiers who took part in the first Gulf war and 413 Iraqi civilians.
The research also showed that for Iraqis who stayed in the country, the risk of depression was more common among soldiers who took part in the war than among civilians.
Previous studies have shown that between 26 and 32 percent of allied troops deployed in the first Gulf war suffered from chronic health problems including memory loss, fatigue, insomnia, muscular pains and respiratory complaints.