Origin of inter-individual differences in stress responsivity in human populations

Abstract

In the past, we have been able to repeatedly show how a specific set of personality variables, dominantly self-esteem and locus of control, are systematically linked to variations in acute and chronic hormonal stress responses. Subjects low in self-esteem show stronger release of cortisol in response to standardized stressor, and fail to habituate upon repeated exposure to stress. In a series of studies involving structural Neuroimaging, we have since investigated the integrity of brain structures involved in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis and thus the endocrine stress response, and have found the volume of the hippocampus (HC) to be systematically and inversely related to the magnitude of the endocrine stress response, and positively correlated to the personality variables self-esteem and locus of control. Further, in a set of functional neuroimaging studies, we were able to show how the central nervous system perceives and processes stress through a network of specific structures in the limbic system and the prefrontal cortex, and how activation changes in the HC and the anterior cingulate specifically seem to be related to the initiation of the endocrine stress response. In summary, these studies contribute to a better understanding of the neural mechanisms of stress processing, and how this is affected by differences in personality. Future studies will aim to determine the impact of these personality differences on brain integrity and endocrine regulation across the life span.