Basal cortisol levels in relation to dimensions and DSM-IV categories of depression and anxiety

The Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV classification may fail to adequately distinguish neuroendocrine factors involved in the etiology of depressive and anxiety disorders. Continuous phenotypic dimensions may correlate better with underlying neuroendocrine dysregulations. We compared the categorical DSM-IV diagnoses with a dimensional approach in the same group of outpatients with depressive (n=36), anxiety (n=18), and comorbid depressive and anxiety (n=19) disorders, who were free of psychotropic medication, and in 36 healthy controls. The Mood and Anxiety Symptom Questionnaire (MASQ) was used to measure the three dimensions of the tripartite model, i.e., anhedonic depression, anxious arousal, and general distress. The salivary cortisol awakening response (CAR) (0, 30, 45, and 60 min after awakening), and diurnal cortisol decline (11:00 h, 15:00 h, 19:00 h, and 23:00 h) were analyzed for linear and nonlinear associations. The CAR showed statistically significant nonlinear relationships with two MASQ dimensions, i.e., anhedonic depression and general distress, but no differences between DSM-IV categories. The diurnal cortisol decline was linearly related to the MASQ dimensions anhedonic depression and general distress and significantly higher AUC(diurnal) levels and a steeper slope were found in depressive patients compared to controls using DSM-IV categories. The present study shows that linear and nonlinear associations with salivary cortisol are detected when using phenotypic dimensions and may be complementary to phenotypic DSM-IV categories when doing neuroendocrine research.