Chronic worriers are significantly more likely to develop post-traumatic stress disorder, a new study that assessed patients before they even developed the condition confirms.

Researchers say that while many people experience traumatic life events like the death of a loved one, being assaulted or witnessing violence, only a small proportion of these people develop PTSD.

"So the question is, 'What's the difference between those who develop PTSD and the majority who don't,'" lead researcher Naomi Breslau, a professor of epidemiology at Michigan State University, said in a statement.

Breslau said that the latest findings, published in the journal Psychological Medicine, reveal that frequent worrying is an important risk factor of the psychological disorder after the decade-long study showed that habitually anxious people are significantly more vulnerable to PTSD.

The study consisted of 1,007 young adults in southeast Michigan. Participants were asked to answer 12 questions designed to measure their neuroticism, a personality trait characterized by chronic anxiety, depression and a tendency to overreact to everyday challenges and disappointments, at the start of the study. Researchers then conducted follow-up assessments on participants at three, five and 10 years after the initial assessment.

Study results indicated that half of the participants had experienced a traumatic event during the 10-year study period. The findings indicated that those who scored higher on the neuroticism scale at the start of the study were significantly more likely to end up being among the 5 percent who later developed PTSD.

Furthermore, researchers added that the findings are particularly convincing because the study assessed participants' personalities before they experienced a traumatic experience rather than measuring neuroticism among those who already had PTSD.

"There have been studies of neuroticism and PTSD, but they've all been retrospective," Breslau explained. "We're never sure of the order of things in a retrospective study. This study sets it in a clear time order."

While there isn't much a person can do to prevent PTSD, researchers say their findings can help health care professionals identify patients with the highest risk of developing the distressing condition and respond accordingly when they do experience trauma.

"We need to be concerned about people with previous psychiatric disorders if there's some kind of catastrophe," Breslau said. "The main thing is that doctors have to look after their patients, ask them questions and get to know them."