A thick cable of nerve cells connecting the right and left sides of the brain (corpus callosum) is smaller than normal in abused children, says Martin Teicher, associate professor of psychiatry at Harvard Medical School. He and his colleagues at McLean Hospital, a psychiatric facility affiliated with Harvard, compared brain scans from 51 patients and 97 healthy children. The researchers concluded that, in boys, neglect was associated with a significant reduction in the size of the important connector. It was also abnormally small in girls who were sexually abused. “We believe that a smaller corpus collosum leads to less integration of the two halves of the brain, and that this can result in dramatic shifts in mood and personality,” Teicher explains.