Revisiting melancholic depression: Review of the concept and clinical implications

Abstract

Introduction Major Depression Disorder (MDD) represents a major concern in mental and public health, being the most common psychiatric disorder and one of the most prevalent diseases in western societies. However, many studies demonstrate a significant heterogeneity in MDD evidenced by different clinical presentations (up to 227 different symptom combinations can be fulfilled to diagnose MDD), different sociodemographic variables, distinct outcomes and significant differences in treatment response. This data may suggest the existence of different ethiopathogenic mechanisms in the development of MDD, implying the review and readjustment of MDD criteria into more distinct and homogeneous subtypes of Depression. Objectives and methods In this non-systematic review the authors sought to identify different subtypes of MDD concerning their 1) clinical features and outcomes, 2) neurocognitive and neurobiological correlates and 3) treatment outcomes. Results An increasing number of studies is being published concerning MDD heterogeneity and its possible subtypes. However, most of the authors try to recognize MDD with Melancholic features (M-MDD) as an independent entity in opposition to the current diagnostic criteria. The suggestion of a distinct MDD subtype is based on several studies showing clinical, cognitive and neurobiological differences shared between M-MDD patients which will be further discussed in this review. Conclusions M-MDD may represent an independent depressive disorder with distinct clinical and outcome implications. However, further research is needed to identify more homogeneous MDD subtypes.