Adding to evidence that the brains of psychopaths are abnormal, Adrian Raine and colleagues have published new data revealing anomalies of the corpus callosum in psychopathic subjects.
The corpus callosum, a thick band of nerve fibers, connects the two cerebral hemispheres, and routes communications between them. Abnormalities of the corpus callosum are linked to a number of brain disorders, ranging from schizophrenia to Fetal Alcohol Syndrome.
Raine and colleagues used structural magnetic resonance imaging to measure the volume of the corpus callosum in 15 men with antisocial personality disorder and high scores on scales of psychopathy, and in 25 controls. The researchers report that compared to controls, the psychopaths showed an increase in callosal white matter volume, an increase in callosal length, a reduction in callosal thickness, and increased connectivity between brain hemispheres. Moreover, Raine et al. report, larger callosal volume was associated with greater affective and interpersonal deficits, lower autonomic stress reactivity (a phenomenon often seen in psychopaths), and low spatial ability.
The researchers theorize that "corpus callosum abnormalities in psychopathic antisocial individuals may reflect atypical neurodevelopmental processes involving an arrest of early axonal pruning or increased white matter myelination."
In an earlier study (see Crime Times, 2000, Vol. 6, No. 2, Page 1), Raine et al. used MRI scans to study the prefrontal area of the cerebral hemispheres in men with antisocial personality disorder. The researchers found that antisocial subjects exhibited an 11 percent reduction in prefrontal gray matter volume when compared with normal controls, a reduction that could not be accounted for by substance abuse or mental illness.
"Corpus callosum abnormalities in psychopathic antisocial individuals," A. Raine, T. Lencz, K. Taylor, J. B. Hellige, S. Bihrle, L. Lacasse, M. Lee, S. Ishikawa, and P. Colletti, Archives of General Psychiatry, Vol. 60, No. 11, November 2003, 1134-42. Address: Adrian Raine, Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, firstname.lastname@example.org.