Application Of Saliva Cortisol In The Diagnosis Of Depression

Background Depression is a common mental disorder that presents with notable depressed mood. The diagnosis of depression is mainly based on clinical manifestations and no ideal objective methods exist. Many researches found hypothalamic-pituitary-adrenal dysfunction in patients with depression. Increasing attention has focused on the relation between salivary cortisol and depression.Objective The aims of this research are to compare morning salivary cortisol between depressed patients and non-depressed individuals, and investigate the application of salivary cortisol testing in clinically evaluating depressive disorder.Methods Morning saliva from 60 depressed subjects (patient group) and 60 non-depressed controls (control group)was collected. Salivary cortisol was analyzed with enzyme linked immunosorbent assay. Depression severity was evaluated with the 24-item Hamilton Rating Scale for Depression.Results Morning salivary cortisol levels in the patient group were significantly higher than those in the control group (P<0.010). A positive correlation was found between salivary cortisol levels and HAMD-24 scores in the control group (Spearman rank correlation coefficient=0.681, P<0.010), but no statistically significant correlation was found in the patient group P=0.240). Receiver operating characteristic curve analysis was used to assess the performance of salivary cortisol in diagnosing depressive disorder. The area under the curve was 0.765 (95% confidence interval,0.679-0.838). The optimal cut-off value of 11.75nmol/L yielded a sensitivity of 65.0% and a specificity of 76.7 %,while the cut-off value of 17.01nmol/L yielded a specificity of 100% and a sensitivity of 41.67%. Depression patients appear to have greater morning salivary cortisol levels than non-depressed individuals. Conclusions Measurement of morning salivary cortisol may be used as a laboratory method to help diagnose patients with depressive disorder, but may not be sufficient to evaluate depression severity in patients.