Contemporary Issues in Depressive Disorders

Abstract

Depression involves a wide range of symptoms affecting mood, cognition, and motor function domains.1 Since depression can be a cause for disability associated with mental health, treating it is regarded as a main source of medical expenditure.2 About 30% of all depressed patients cannot achieve remission despite being fully treated with two or more antidepressants.3 Moreover, the great unmet need in the realm of psychopharmacological treatment for depression has been identified by the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study.4 This special issue aims to comprehensively review the contemporary research approaches for 1) diagnostic issues,5 2) pharmacogenetics,6 3) epigenetics,7 and 4) potential neuroimaging biomarkers8 in depressive disorders. The fourth edition (DSM-IV) to DSM-5, revision of the Diagnostic and Statistical Manual of Mental Disorders places greater emphasis on the dimensional versus the categorical approach, in defining the symptoms criteria for major depressive disorder (MDD). Thus, the dichotomization of mood disorders into bipolar affective disorder and unipolar depressive disorder, application of trans-diagnostic specifiers including “with psychotic features,” “with mixed features,” and “with anxious features,” addition of “hopelessness” as the descriptor of a depressive mood, and elimination of “bereavement exclusion” are newly applied to define MDD in the DSM-5.5 Furthermore, because the operational criteria for MDD consist of nine symptoms in the DSM-5, the heterogeneity of the depressive syndrome can inevitably be invoked and criticized from the viewpoint of Wittgenstein’s “games” analogy.1,9,10 However, network analysis of symptoms in MDD patients may provide new insight regarding the definition of MDD.11 Additionally, the node and edge statistics of MDD symptoms may be supported by neurobiological underpinnings in future studies. Gene variants coding for cytochromes that are involved in antidepressant metabolism (CYP2D6 and CYP2C19), are considered promising biomarkers based on considerable eviPrint ISSN 1738-3684 / On-line ISSN 1976-3026 OPEN ACCESS