Many factors contribute to post-traumatic stress disorder (PTSD), not just fear during trauma, a new study has found.

People who suffer a panic attack during or immediately after a traumatic event aren't at increased risk of developing PTSD, according to the new study published in the April issue of the journal Psychiatry Research.

The study challenges earlier findings that having a panic attack during or after an upsetting event triggers or predicts PTSD in the long term.

Factors such as a prior history of depression, a person's emotional support network and self-esteem are stronger indicators of a person's likelihood of developing PTSD, according to the study conducted by researchers at the Geisinger Health System in Danville, Pennsylvania.

The study authors examined panic attacks during a traumatic experience among people exposed to the 9/11 World Trade Center terror attacks.

The study found that 30 percent of people who suffered panic attacks after 9/11 had depression prior to the event. Other findings included the highest rate of panic attacks occurred in those aged 30 to 44, people with the highest levels of education were least likely to suffer a panic attack and Hispanics were more likely to have panic attacks than people in other ethnic groups.

Clinicians should look at other signs of mental-health stress such as not sleeping, recently experiencing stressful life events and withdrawing from social interactions, the study suggested.

Symptoms of panic attacks include shortness of breath, sweating, trembling or shaking, heart pounding, chills or hot flashes, and a sense that there is no reality.

About 10 percent of Americans suffer panic attacks each year, but that rate is much higher among people involved in traumatic events, according to federal government data.

(Xinhua News Agency April 13, 2009)