Washington, June 20 (Reuters): The brains of shy people overreact when they see strange new faces, which may explain personality differences and also offer ways to treat anxiety disorders, US researchers said today.
Even people who have seemingly overcome their innate shyness have an extra-strong reaction in the amygdala, the emotional centre of the brain, when shown a new face, the researchers found.
“It’s been theorised that the behavioural differences that characterise inhibited and uninhibited children may relate to the amygdala’s response to novelty, and our study supports that concept,” said Dr Carl Schwartz, an assistant professor of psychiatry at Harvard Medical School and Massachusetts General Hospital who led the study.
Schwartz and colleagues tested 22 adults in their 20s who had taken part in an earlier study. Thirteen of them had been characterised as inhibited when they were two-years-old, and nine as uninhibited.
“Inhibited children in the second year of life don’t like novelty, don’t like unknown situations,” Schwartz said in a telephone interview. “It is broader than shyness ... It is about being more vigilant about things that are new.”
He said about two-thirds of children identified as inhibited as toddlers lost overt signs of those characteristics by adolescence. Of the 13 in the study who were inhibited at age 2, two went on to develop clinical anxiety disorders.
Anxiety disorder, he said, can be seriously disabling. “It is a psychiatric disorder that you might define as shyness on steroids,” he said.
“These are kids who don’t want to go to school. They don’t date.”
Schwartz’s team used a type of brain scan called functional magnetic resonance imaging to watch the brains of their volunteers. They showed the 22 people pictures of faces, sometimes repeating the same face and sometimes throwing new ones into the sequence.
Everyone’s amygdala lit up a little bit when a new face was seen. But those who had been characterised as inhibited as toddlers showed an exaggerated response, Schwartz’s team reports in today’s issue of the journal Science.
Schwartz said the study was very small and will have to be repeated in larger groups.
He also said it would be interesting to look at the brains of babies and toddlers to see if the differences are innate — or if in fact they develop as people get older.
Inhibited children have a greater risk of developing anxiety disorder but are in no way fated to do so, Schwartz stressed.