SHY TODDLERS are likely to grow into shy adults whose emotional inhibitions put them at greater risk of developing more serious mental disturbances in later life, a 20-year study has found.
An inhibited temperament - marked by features such as shyness, caution or withdrawal - tended to stay with someone for life and was linked with hyperactivity in a region of the brain known as the "seat of fear".
Scientists analysed the behaviour and brain patterns of 22 young adults whom they had interviewed twice before, once as early teenagers and once as small children.
They were particularly interested in the way the brain's amygdala - an almond-sized structure known to initiate fearful emotions - responded, as measured by a brain scanner, to the sight of strangers, a well-tested measure of shyness.
Carl Schwartz, a psychologist at the Massachusetts General Hospital and Harvard Medical School in Boston, said there was a clear division in the way the amygdala responded between those who were shy as children and those who were less inhibited.
"Our findings both support the theory that differences in temperament are related to differences in amygdala function, something earlier technology could not prove, and show that the footprint of temperamental differences observed when people are younger persist and can be measured when they get older," Dr Schwartz said.
The research suggests that there is a strong genetic component to a person's temperament, which predisposes them to either shyness or sociability, caution or boldness, withdrawal or approach.
At the two extremes, inhibited children tend to be timid with new people, objects or situations while uninhibited children will approach them spontaneously without any apparent fear.
When the subjects were having their brains scanned they were shown photographs of different faces, some of familiar people, others of strangers. …