How well children are cared for in their first two years directly affects brain development and IQ later in life, a new study finds.

Researchers studied abandoned young children in Romanian orphanages over time and found that those placed in foster care at younger ages had significantly higher IQ's than those placed in foster care after the age of 2.

"Our findings suggest that there may be a sensitive period in the first two years of life in which experiences are especially important in shaping cognitive development," said principal investigator Charles Zeanah, professor and chief of child psychiatry at Tulane University School of Medicine. “This work adds to a growing body of scientific evidence about the importance of early relationship experiences.”

The research, done in collaboration with scientists at Harvard University, the University of Maryland and Temple University, is detailed in the Dec. 21 issue of the journal Science.

The study tracked 136 children between the ages of six months to 30 months who had been abandoned at birth or soon thereafter and placed into institutions in Bucharest, Romania. Researchers trained social workers and recruited Romanian families to provide foster care for half the children who were randomly selected.

Children placed in foster care within the first 18 months of life had the greatest gains in cognitive development compared to those placed in foster care later. For example, at the age of 42 months, those placed in foster care before 18 months old had an average IQ of 94 compared with scores of 89 for similarly aged children placed in foster care starting between 18 to 24 months.

The cognitive gains were less impressive for those placed in foster families between the ages of 24 to 30 months.

A follow-up survey of the same children one year later showed that IQ's of the two groups placed in foster care after two years of age continued to significantly lag behind the group sooner placed with families.

The results suggest that in any country, foster families are better than institutionalized care for very young children, the researchers said.