Keywords: Major depressive disorder Antidepressant treatment Noradrenergic and specific serotonergic antidepressant Mirtazapine Mianserin

Since selective serotonin reuptake inhibitors, that are recommended as first-line antidepressant psychopharmacotherapy for major depressive disorder (MDD), may not be the optimal choice for every patient, antidepressants with different modes of action exerting a distinct set of expectant effects, represent a valuable alternative. Despite the previously observed increased prescription rates of noradrenergic and specific serotonergic antidepressants (NaSSAs) particularly mirtazapine in Europe, the individual profiles of patients primarily prescribed NaSSAs in real-world settings have not been systematically investigated yet. In this secondary analysis based on a European, cross-sectional, naturalistic, multicenter study involving 1410 adult males and females with primary MDD, sociodemographic and clinical variables were compared between patients dispensed NaSSAs and those with alternative first-line antidepressants. Hereby, NaSSAs were administered in 8.6 % of the sample (mirtazapine: n = 114, mianserin: n = 7). We detected associations with older mean age, male sex, unemployment, as well as additional melancholic and catatonic features, inpatient treatment, lower mean daily dosages of the administered antidepressants but higher rates of augmentation with low-potency antipsychotics, and greater mean reductions of depressive symptoms during their current major depressive episodes. Although the study design is unsuitable to draw any causal conclusions, our findings provide a realistic picture of patients eligible for first-line antidepressant treatment with NaSSAs, especially mirtazapine, and underscore the role of this AD substance class in severe MDD. Further, they may represent a promising basis for future systematic research focusing on precision diagnostics and treatment in MDD, that would ideally result in faster responses and better outcomes, especially in the so-called difficult-to-treat conditions including treatment resistant depression.