Disentangling the effects of depression and perceived stress on cortisol levels in individuals with obesity: Preliminary results from a cross-sectional study

Background: Hypothalamic-pituitary-adrenal (HPA) axis dysregulation has been suggested to play a role in the association between depression and obesity. The study aimed to investigate differences in cortisol levels in in-dividuals with obesity with and without depression and the role of perceived stress on these differences.Methods: Saliva samples were collected at awakening, 15-, 30-and 60-minutes post-awakening from 66 in-dividuals with obesity (30 with major depressive disorder and 36 without major depressive disorder). Salivary cortisol was analysed using ELISA technique. Linear Mixed Models were used for group differences in cortisol awakening response (CAR) with adjustment for socio-demographic confounders and binge eating.Results: Individuals with obesity and depression had lower CAR compared with individuals with obesity without depression (8 =-0.44; p = 0.036). When controlling for perceived stress, CAR was no longer influenced by depression (8 =-0.09; p = 0.75), but individuals with moderate/high stress had lower CAR compared with those with low stress (8 =-0.63; p = 0.036).Conclusions: Our results suggest that differences in CAR between individuals with obesity with and without depression could be due to higher levels of perceived stress in the depressed subjects.