The impact of intrauterine exposure versus postnatal environment in neurodevelopmental toxicity: long-term neurobehavioral studies in children at risk for developmental disorders.

Various investigators have shown that enriched environment may positively affect the early brain development of experimental animals. Environment was also shown to positively affect the development of young children born to mothers of low socio-economic class (low SES). It is unknown, however, to what extent can an enriched environment improve the developmental outcome of children born with slight brain damage. We studied the development of preschool and early school age children born to heroin dependent parents raised at home or adopted in comparison to children suffering only from environmental deprivation (low parental SES) and to controls. They were examined by several professionals, using standard, age appropriate, neurological and psychological tests. Similar evaluations were performed on a group of early school age children born to mothers with pregestational or with gestational diabetes and on a group of children born prematurely, with a birth weight of less than 1500 g using various developmental tests. Young children born to heroin dependent mothers and fathers raised at home and children of low SES had, in comparison to controls, lower intellectual skills and a higher rate of inattention. This persisted at school age, too. Children born to heroin dependent mothers adopted at a young age and hence being raised in a good environment had normal intellectual function but a high rate of inattention and behavioral problems. We also examined the school age children for possible presence of ADHD and found a high rate of ADHD among all children born to heroin dependent parents including those adopted, as well as in the children with low parental SES. Similar findings regarding the strong positive influence of an enriched environment were observed in children born to diabetic mothers, where the intellectual abilities of the children were directly related with parental education. The cognitive abilities of the children born prematurely were also strongly associated with parental education and not with the degree of perinatal complications. In conclusion, in all groups of children at high risk for developmental problems was found that the environment has a strong influence on their intellectual abilities but not on motor skills or attention span. A good environment (high parental SES) may significantly improve the outcome.