Stress and serum cortisol levels in major depressive disorder: a cross-sectional study

Major depressive disorder (MDD) is one of the disorders that most causes disability and affects about 265 million people worldwide, according to the World Health Organization (WHO). Chronic stress is one of the most prevalent factors that trigger MDD. Among the most relevant biological mechanisms that mediate stress and MDD are changes in the hypothalamic-pituitary-adrenal (HPA) axis function. Hypercortisolism is one of the relevant mechanisms involved in response to stress and is present in many people with MDD and in animals subjected to stress in the laboratory. This study aimed to investigate the levels of stress and cortisol in individuals diagnosed with MDD from the Basic Health Unit (BHU) in a small city in the western region of Santa Catarina, Brazil. Depression scores were assessed using Beck's inventory. For the investigation of stress, an adaptation with twenty-four questions of the Checklist-90-R manual was performed. The analysis of the cortisol levels in the individuals' serum was by the chemiluminescence method. Depression and stress scores were significantly higher in individuals with MDD than in control subjects (p < 0.001). Cortisol levels were also significantly higher in individuals with MDD (p < 0.05). Besides, depression scores were positively correlated with stress scores in individuals with MDD (Pearson's "r" = 0.70). Conclusion: Individuals with MDD had higher stress levels and cortisol than control subjects. The positive correlation between the levels of stress and depression in MDD individuals suggests that these conditions are related to a dysregulation of the HPA axis function.