Different forms of early childhood trauma can increase the risk for mental illness in adulthood. Scientists of Charité University Medicine in Berlin, Germany, and McGill University, have now discovered a neural basis for this association. Their study, published in the current issue of the American Journal of Psychiatry, shows that sexually abused and emotionally maltreated children exhibit changes in the architecture of their brain that reflect the nature of the maltreatment.
Victims of childhood maltreatment or sexual abuse often suffer from serious psychiatric disorders as well as sexual dysfunction. The underlying mechanisms mediating this association are poorly understood. A group of scientists lead by Prof. Christine Heim, Director of the Institute of Medical Psychology at Charité University Medicine Berlin, together with Prof. Jens Pruessner, Director of the McGill Centre for Studies in Aging, at McGill University used magnetic resonance imaging (MRI) to examine 51 adult women who were exposed to various forms of childhood maltreatment. The scientists measured the thickness of the cerebral cortex, where sensations from all parts of the body are processed.
The results showed a correlation between specific forms of maltreatment and thinning of the cortex in precisely the regions of the brain that are involved in the perception or processing of the abuse. "The large effect and the regional specificity in the brain that corresponds to the type of abuse is remarkable”, says Prof. Pruessner, also Associate Professor at the Douglas Mental Health University Institute. For example, the somatosensory cortex in the areas in which the female genitalia are represented was significantly thinner in women who were victims of sexual abuse in their childhood. Victims of emotional maltreatment, in contrast, showed a specific reduction of the thickness of the cerebral cortex in areas associated with self-awareness and emotional regulation.
"Our data point to a specific connection between experience-dependent neural plasticity and later health problems", says Prof. Heim. The scientists speculate that a regional thinning of the cortex may be a result of the activity of inhibitory circuits, which could be interpreted as a protective mechanism of the brain that may shield the child from the initial experience but leads to health problems later in life. The results fit into the general literature on neural plasticity and show that cortical representation fields can be smaller when certain sensory experiences are disadvantageous. The study was further conducted in collaboration with Helen Mayberg from Emory University, Atlanta, Georgia, and Charles Nemeroff from University of Miami, Florida.