Chronic stress exposure, diurnal cortisol slope, and implications for mood and fatigue: Moderation by multilocus HPA-Axis genetic variation.

Chronic stress exposure has been shown to alter hypothalamic-pituitary-adrenal (HPA) axis functioning, which may mediate its effects on psychopathology and negative health outcomes. The nature of the chronic stress-HPA axis dysregulation is unclear and individuals likely vary in the extent to and manner in which indices of HPA axis regulation, such as diurnal cortisol slope, are influenced by chronic stress. We examined whether HPA-axis-linked genetic variation moderates the association between chronic stress and diurnal cortisol slope, and potential implications for mood and fatigue (possible manifestations of negative clinical outcomes). 211 adolescents (M age 15.89, 54.5% female) completed chronic stress interviews and provided DNA samples. Participants then provided saliva samples at waking and 12 h post-waking for two consecutive weekdays. HPA-axis genetic variation was calculated using a multilocus genetic profile score (MGPS) approach, using ten SNPs from CRHR1, NR3C1, NR3C2, and FKBP5 to generate an additive score of HPA-axis-linked genetic risk. Neither chronic stress nor MGPS directly predicted diurnal slope, but MGPS moderated the association between chronic stress and diurnal slope, with stress predicting a high waking cortisol followed by steep slope among youth with low but not high MGPS scores. MGPS also interacted with chronic stress to predict both negative affect and fatigue, and moderated the indirect effect of chronic stress on mood and fatigue via diurnal slope. Results suggest that diurnal cortisol regulation may be one mechanism by which genetic risk intensifies the association between chronic stress and negative outcomes.