The last decade has seen a vast increase in knowledge of how the human brain develops. It has been demonstrated that both the establishment of synaptic connections between neurones and the programming of neurochemical responses that have an effect on the whole body are dependent on experience. The most sensitive period for brain growth, the time of optimal plasticity, is over the first two or three years of life. If the baby's neurological development is threatened by abuse or neglect, which includes excessive attachment disruption, the damage may set its stamp on the rest of life.