Some people handle fear better than others. Now, research shows one possible reason why.

It’s not about nerves of steel, but the thickness of a specific brain area.

That area is called ventromedial prefrontal cortex. It took center stage in a recent fear test.

When some people started showing fear, others stayed calmer. Their secret: a thicker ventromedial prefrontal cortex an area of the lower surface of the brain.

The study appears online in the Proceedings of the National Academy of Sciences.

Read WebMD's "What Makes People Flinch?"

Finding May Tie In With Anxiety

“We’ve always wondered why some people who are exposed to traumatic experiences go on to develop anxiety disorders like posttraumatic stress disorder and others do not,” states researcher Mohammed Milad, PhD, in a news release. “We think this study provides some potential answers,” he continues.

Milad is a research fellow in the psychiatry department of Massachusetts General Hospital in Boston.

Read WebMD's "We Humans Know Fear When We See It"

Creating, Then Destroying Fear

Milad’s study included 14 healthy young adults.

Subjects sat in front of a computer monitor. They wore electrodes on the second and third fingers of their dominant hand.

On the screen, they saw photos of a conference room with a blue or red lighted lamp. Meanwhile, they got “highly annoying but not painful” electric shocks through the electrodes.

That happened five times. Then, the pictures were shown 10 more times, without the shock.

The researchers’ goal: Build up fear by linking the photos and the shocks, and then break the pattern to extinguish fear.

Read WebMD's "Fear From Our Forefathers?"

Fear, Defeated

The subjects returned the next day.

This time, there were no shocks. Instead, they wore skin monitors as they viewed the same pictures as the previous day. Monitoring the skin was an indirect measure of the participants’ reaction to the photos and the subsequent electric shock which had followed them in earlier parts of the experiment.

The researchers used brain scans to measure ventromedial prefrontal cortex thickness, a brain area implicated in fear extinction.

Those with a thicker brain region were apparently less disturbed by the pictures. They showed smaller skin reactions to the photos, the data shows.

Such thickness varies from person to person. That variability “may account for risk [or resilience] factors for anxiety disorders,” write the researchers.

Future studies should test whether brain thickness predicts therapeutic response to behavioral therapies for anxiety disorders, they write.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Milad, M. Proceedings of the National Academy of Sciences, online edition, July 11-15, 2005. News release, Massachusetts General Hospital. News release, Proceedings of the National Academy of Sciences.