"In order to have that normal development, it requires stable interaction with adults," DeFazio said.

How to prevent toxic stress

Healthy interaction with children can prevent toxic stress. Unhealthy or a lack of interaction can promote it.

Compared with children whose parents have a higher education level and are in better financial condition, when children from poor families enter school, "There is already this achievement gap," said Kelly Swanson, communications director for the Early Learning Investment Commission, in Harrisburg, which consists of business leaders throughout the state who recognize that early childhood education and intervention is ultimately a work force development issue.

Some preschool programs can help children with development delays reach their proper maturation level before entering school.

"Kindergarten teachers have said they can tell immediately who had pre-kindergarten," Swanson said.

They are usually the ones found playing well and understanding how to follow directions.

"When they come in without those skills, teachers spend a lot more time getting children to focus and sit in their seats," Swanson said.

Brain's architecture changes

If toxic stress occurs before age 6 -- a crucial time when the brain is developing -- the brain's architecture changes, interrupting the brain's functional development, or brain power, Swanson said.

The result is lower IQs, and negative effects on a child's personality. Also, these children will have increased incidents of chronic adult diseases.

Prior to age 3, children don't have explicit memories, said Hoover, the pediatric neuropsychologist, but they do develop a sense of security that they carry with them throughout life.

Though no one can visualize the connections of synapses, Hoover said evidence shows children who experience trauma through abuse in general have smaller brain volumes.

Negative experiences early in life almost always lead to the overwiring of the limbic system, or the emotional brain, she said, and these children are more often on the verge of a tantrum.

"Life experiences do have a reciprocal affect on brain function," Hoover said. However, "Children can be exposed to trauma and abuse, and can still develop into well-functioning adults."