Shyness is inherited

Main Category: Public Health
Article Date: 21 Jun 2003 - 0:00 PDT


A shy child may learn to be more outgoing, but a study suggests that shy temperament may be inherited and a brain marker for it does not change as the person ages.

In the study, which appears this week in the journal Science, researchers conducted brain scans on 22-year-olds and found that those who had been classified 20 years before as inhibited or shy children had a distinctive reaction in their brains when confronted with novel images.

People who had been judged as toddlers to be inhibited showed in the scans that the amygdala structure in their brains responded much more actively to unexpected sights than did those subjects who had been judged as children to be more outgoing, said Jerome Kagan, a researcher in the department of psychology at Harvard University.

'That is support for the notion that the reason they were shy, timid and reserved when they were 2 years old is because they had an excitable amygdala,' said Kagan. This suggests that shyness is a temperament that can be inherited, but the researcher said this temperament does not necessarily determine one's eventual personality.

'They are now 22 years old,' Kagan said of the test subjects. 'A lot of the ones who were fearful aren't fearful anymore. They have overcome it. But the question is, did they still have a very active amygdala.'

Based on the brain scans, Kagan said, the answer is clearly yes.

Tests were conducted on 13 people who had been evaluated as shy as 2-year-olds. The results were compared tests on nine people who had been evaluated as children to be outgoing and bold.

'We had assumed, but never measured, that ... the shy, inhibited group had inherited a certain chemistry' in the amygdala, Kagan said.

All the subjects were exposed to a series of pictures of faces with neutral expressions. After the people had become accustomed to those pictures, new faces were introduced while the researchers measured the reaction of the amygdala structure in their brains using magnetic resonance imaging.

The brains of the once-shy children were much more active than the other subjects.

Kagan said that before any firm conclusions can be drawn there needs to be a similar research using many more subjects than the 22 in the current study.

Although some children are shy and others are outgoing, he said, these traits can change with time and life experiences.

'People overcome their shyness,' Kagan said. 'You can also acquire shyness.'

Extreme shyness can be a precursor for serious disorders, such as social phobias and depression. Kagan said that by finding the biological basis for such shyness, it may be possible to develop drugs to treat patients whose lives are adversely affected by the condition.

Other co-authors of the study are Dr. Carl E. Schwartz, Dr. Christopher I. Wright, Lisa M. Shin and Dr. Scott L. Rauch, all of the Harvard Medical School.

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