In his study of children, Perry found that there is no increase in the size of the child's brain who was removed from neglectful environment at the age of five.
It is commonly due to the fact that a human brain develops most of its neural and cognitive systems at the age of five.
His study provides proofs that social and emotional development in early childhood development drives better educational, health, social and economic outcomes. Hence providing us the evidence that children who are taken out of such hopeless neglected environment at the age of five don't have noticeable changes in their brain growth. If they were removed before the age of five, there are chances of their strong mental growth.