This Non-Interventional Study (NIS) is intended to evaluate the duration of treatment with an initial antidepressant taken as monotherapy in patients in whom treatment was changed because of suboptimal response at physician's discretion. This will address unmet medical needs of patients with a depressive episode related to RDD (ICD-10, Version 2010), who have failed to respond adequately to initial treatment with an antidepressant and contribute to an understanding of the usual approaches that physicians adopt to monitor initial treatment efficacy in RDD (Recurrent Depressive Disorder). The study will also focus on second-line therapy in hard to treat patients, describing the different pharmacotherapeutic strategies.