Abuse, neglect, cruelty and psychological cruelty affect how the mind develops.

A great deal of work has now been carried out on the long term effects of childhood abuse and there is clear evidence that the effects of the maltreatment of a child will have broad reaching effects on the child's ability to function well within the family, socially and in education. Children can develop a wide range of psychological disorders and the longer the abuse lasts the greater and more chronic the disorders will be. Many of these disorders will not become apparent until puberty or later. Although it is not at this time clear why, many people experience remembering abuse around the age of thirty. This appears to be some kind of watershed and much more work needs to be done in this area. 

Childhood maltreatment changes how the brain develops and its chemical structure. Many victims of abuse are unable to experience happiness and have great difficult in having fun or playing. Intuitively this makes sense, the brain cannot develop or incorporate something that is absent from the child's life. The brain is not a static object making available all things to all people, it is a developing organism. If a child is denied affection, then whichever part of the brain deals with affection becomes stunted. Just as there isn't some magical part of the brain that knows math, if a child is never taught math then it will be simply absent and again whatever part of the brain that deals with math will not develop. 

It must be remembered that a child is not a mini adult with a fully developed brain, s/he is a work in progress, a growing and developing being. 

It is fashionable at this time to witch hunt paedophiles, undoubtedly a heinous crime, yet constantly calling a child clumsy or stupid will have a dramatic effect on their development, eroding their confidence, their development, academic ability, their social behaviour and ability make friends and form relationships. That old expression, 'Sticks and stones may break my bones but names will never hurt me', is as ludicrous as it is wrong. Bones are far easier to repair than minds.
 

Reference material.

2011 Keith Lindsay-Cameron.