Studies of children raised in poor environments show that they have cognitive deficits of substantial magnitude by 18 months of age. Full reversal of these deficits may not be possible. The influence of early environment on brain development is long lasting. The first group demonstrated significantly more complex brain function at age 12. The positive effects appear to be even greater at age 15, suggestion that over time, the benefits of early intervention are cumulative.
Early stress can impair brain function.
A child's social environment can activate hormones in ways that adversely affect brain functions, including learning and memory. These effects may be permanent. Children who have experienced extreme stress in their earliest years have proven to be at greater risk for developing a variety of cognitive, behavioral, and emotional difficulties. Optimum brain development has an even greater benefit for those children born at an economic or health disadvantage.