Genes plus parenting may promote shyness, anxiety

NEW YORK (Reuters Health) - A mother whose child has a naturally fearful temperament may act less nurturing toward the child, triggering a vicious cycle of behavior that reinforces the child's fearfulness and shyness, researchers propose.

In previous work, Dr. Nathan A. Fox of the University of Maryland, College Park, and colleagues found that children carrying one or two short versions of a gene involved in transport of the neurotransmitter serotonin were more likely to be extremely shy at age 7 if their mothers reported little social support. If their mothers had plenty of social support, kids carrying the so-called "shy gene" were at no greater risk of shyness.

But children with two long versions of the serotonin transporter gene -- meaning they were free of the shy gene -- were normally outgoing at age 7 no matter how little social support their mothers received.

The team's latest research, reported in the journal Current Directions in Psychological Science, points to a possible mechanism by which a mother's lack of social support might reinforce a child's tendency toward withdrawn behavior.

Fox and colleagues observed that people carrying two copies of the "shy gene" are more likely to react poorly to life stresses by becoming depressed or developing other maladaptive behavior, while those who don't carry the gene seem to be somewhat shielded from stress. Individuals with just one copy of the shy gene "fall somewhere in the middle."

When mothers have enough social support they are more sensitive and nurturing toward their child, but mothers with less support are less sensitive, Fox and colleagues observed.

"Taken together, this research suggests that quality of maternal care giving behavior shapes the development of behavioral inhibition, perhaps by altering the neural systems that underlie reactivity to stress and novelty," the researchers note.

Stressed-out parents may also tend to focus their child's attention on negative events, the researchers add, which leads to a phenomenon called "attention bias" toward threat, making them more likely to see threats in their environment and to focus more intensely on these threats.

These influences can then lead to changes in brain circuitry that promote anxiety and fear "well into adulthood," the researchers conclude.

SOURCE: Current Directions in Psychological Science, February 2007,