Authorities report that more than half the population experiences trauma, which makes people more likely to develop PTSD, depression, anxiety and physical illness later in life.

Now, a new study finds that among ‘healthy’ individuals, those who display good resiliency, experiencing trauma increases the brains’ sensitivity to upsetting stimuli.

That is the finding of a new Cornell study that excluded people who did not have such mental disorders as post-traumatic stress disorder (PTSD) or major depression. One of the first studies to look at the effects of trauma on the brains of healthy people, it is published in the May issue of the journal Emotion.

“These people appear to be doing okay, but they may, indeed, be having more sensitive responses to upsetting stimuli,” said Elise Temple, a co-author and assistant professor of human development at Cornell.

Also, trauma has been found to make the brain’s emotional processing centers — particularly the amygdalae, the parts of the brain that judge emotional intensity and make emotional memories — more sensitive in cases of PTSD.

The findings suggest that events that trigger shock, fear and horror that are within a normal range — may cause similar changes in the brain that traumas do.

Victims may experience lingering symptoms (bad dreams, jumpiness, thinking about the incident and avoiding the site of the trauma), but they are not severe.

However, the kinds of changes that these traumas cause in the brain, the researchers suspect, create vulnerability to developing future mental disorders.

Specifically, the Cornell researchers found that three years after Sept. 11, 2001, the amygdalae were most sensitive in those who were close to the World Trade Center.

These individuals tended to still experience lingering symptoms that were not severe enough to be diagnosed as a mental disorder. Those with lingering symptoms showed significantly more sensitive emotional reactions in the brain when stimulated by photographs of fearful faces.

“Our study suggests that there may be long-term neural correlates of trauma exposure, even in people who have looked resilient,” said lead author Barbara Ganzel. “Up until now, there has been very little evidence of that.”

“People who had experienced traumas that left them with more lingering symptoms were the ones who had higher activity in their fear centers,” said Temple. “We think that the World Trade Center experience was traumatic enough that it left them with hyperactive amygdalae.”

Source: Cornell University