Hypothalamic-pituitary-adrenal axis hyperactivity and brain differences in healthy women

Background: Previous studies have suggested that dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis leads to brain changes. However, few studies have examined the whole brain configuration for an association with HPA axis activity. We examined the relationship between HPA axis activity and the whole brain configuration. Methods: The subjects in this study were 34 healthy female volunteers. HPA axis activity was assessed by the dexamethasone/ corticotropin-releasing hormone test. Structural volumes of the brain and diffusion tensor images were obtained, and correlations were evaluated voxel-wise. Results: There was a significantly negative correlation between fractional anisotropy value and cortisol levels at 16:00 h (CL-2) in the anterior cingulum, left parahippocampus and right occipital region. There were significantly positive correlations between mean diffusivity value and CL-2 in the left hippocampus and bilateral parahippocampal regions. Conclusions: Our data suggest that reduced feedback of the HPA axis is associated with reduced neural connectivity throughout the brain, and such an association may be strong in the anterior cingulate, the hippocampus and the parahippocampal regions.