The Effect of Abuse, Neglect, and Stress on Brain Development
At the CIVITAS Child Trauma Programs at Baylor College of Medicine, Bruce Perry and co-workers have studied the impact of neglect and trauma on the neurobiology of over 1,000 abused and neglected children. In one study, 20 children who had been raised in globally under-stimulating environments- children who were rarely touched or spoken to and who had little opportunity to explore and experiment with toys- were examined with sophisticated brain-imaging techniques and other measures of brain growth. The children were found to have brains that were physically 20 to 30 percent smaller than most children their age and, in over half the cases, parts of the children's brains appeared to have literally wasted away.
— "Starting Smart: How early experiences affect brain development, An Ounce of Prevention Fund", 1996.
The Effect of Stress:
The relationships children have with their caregivers play critical roles in regulating stress hormone production during the early years of life. Infants and young children who have secure relationships have a more controlled stress hormone reaction when they are upset or frightened because they anticipate safety and comfort. This means that they are able to explore the world, meet challenges, and be frightened at times without producing excess amounts of hormones such as cortisol that trigger the brain to respond to a crisis. In contrast, children whose relationships are insecure or disorganized have higher stress hormone levels when they are even mildly frightened because their bodies are conditioned to treat all stress as crisis. These increased cortisol levels may alter the development of brain circuits in ways that make some children less capable of coping effectively with stress as they grow up.
Young children who are neglected or maltreated have abnormal patterns of cortisol production that can last even after the child has been moved to a safe and loving home. This is especially true for children who show symptoms of post-traumatic stress, even if they are not diagnosed with post-traumatic stress disorder. (Excessive Stress Disrupts the Architecture of the Developing Brain (2005) National Scientific Council on the Developing Child)