Unraveling the effects of plasticity and pain on personality

Chronic pain resulting from physical stressors is often accompanied by psychological disorders such as depression. Although depressive disorders are associated with changes in brain anatomy, it remains unknown if changes in brain anatomy associated with increased state depression levels also occur in patients with chronic pain. When individuals are experiencing physical stressors such as ongoing pain, depressive personality traits may predispose them to develop depressive states. The aim of this study was to use brain morphometry to determine the interaction among chronic pain, state and trait depression, and regional brain structure. We investigated regional gray matter volume in 42 chronic pain patients and 35 controls using voxel-based morphometry of T1-weighted anatomical images. Significant relationships between regional gray matter volume and state or trait depressive values were determined. In chronic pain patients, state depression scores were significantly correlated to subtle changes in the thalamus and the cingulate, dorsolateral prefrontal, and hippocampal cortices. These same brain regions were also significantly correlated to trait depressive scores. Unexpectedly, gray matter volumes in these regions were not correlated to trait depressive scores in healthy controls. Because trait depressive values were not correlated to gray matter in controls, but were so in chronic pain patients, these data strongly suggest that subtle changes in brain anatomy can evoke changes in individuals' trait depression values. If these regional gray matter changes are severe enough, changes in an individual's personality trait may result.

This study demonstrates anatomical brain alterations associated with both state and trait depression in chronic pain patients. Because our study reveals that trait depression is not correlated to the anatomy of these regions in healthy controls, ongoing pain itself may result in anatomical changes that in turn can alter an individual's personality.