High and low neuroticism predict different cortisol responses to the combined dexamethasone–CRH test

Background:Depression and posttraumatic stress disorder are both associated with altered function of the hypothalamic–pituitary–adrenal axis. Neuroticism is a strong predisposing factor for depression and probably also a risk factor for posttraumatic stress disorder. This study investigated whether young adults with high and low neuroticism scores show differences in hypothalamic–pituitary–adrenal axis regulation that might relate to their differential vulnerability to psychopathology. Methods:Neuroticism was measured with the Eysenck Personality Questionnaire in 258 students aged 18–25. Fourteen scoring in each of the upper and lower quartiles of the neuroticism distribution according to gender participated in a combined dexamethasone–corticotropin-releasing hormone test. Results:Low-neuroticism individuals showed a significantly greater cortisol response than high-neuroticism individuals. Conclusions:The mechanism of this effect remains to be elucidated. High-neuroticism subjects may have a downregulated hypothalamic–pituitary–adrenal axis to prevent harmful overactivation. This is the first demonstration of a difference in hypothalamic–pituitary–adrenal axis regulation associated with neuroticism.