Mixed anxiety–depressive disorder and major depressive disorder: comparison of the severity of illness and biological variables

Mixed anxiety–depressive disorder (MADD) is a new diagnostic category defining patients who suffer from both anxiety and depressive symptoms of limited and equal intensity accompanied by at least some autonomic features. Patients do not meet the criteria for specific anxiety or depressive disorders. The emergence of the symptoms is independent of stressful life events. There are many issues presently under investigation about the validity of this clinical entity. In this study, a group of 29 patients with MADD was compared with a group of 31 patients with major depressive disorder (MDD) to assess the differences and similarities between these two disease categories in terms of severity measures and biological variables. The dexamethasone suppression test (DST) was employed, and thyroid hormones and thyrotropin (TSH) levels were measured for the evaluation of hypothalamic–pituitary–adrenal (HPA) and hypothalamic–pituitary–thyroid (HPT) axes, respectively. The patients with MADD were found to be less depressive and more anxious compared to those with MDD. DST responses and thyroid functions were found to be similar in the two groups. When severity of depression was controlled, k max and 2300-h cortisol values were found to be significantly higher in the MADD group. Although the patients with MDD and MADD presented with relatively different clinical features, there is not enough biological evidence indicating that MADD represents a discrete diagnostic category. However, there may be relatively higher HPA activity in MADD patients.