Depression subtypes and inflammation: Atypical rather than melancholic depression is linked with immunometabolic dysregulations

The link between inflammation and major depressive disorder (MDD) has been widely established. But as MDD is a highly heterogeneous disorder, the association with inflammation may not be present in all persons with MDD. In this chapter, we discuss the relevance of studying depression subtypes in association to inflammation, in particular atypical and melancholic depressive subtypes. We then summarize the available literature on inflammation in atypical and melancholic depression and discuss the (methodological) limitations of the literature. Furthermore, clinical implications and relevance to treatment are discussed, including newer treatment options such as adjuvant anti-inflammatory medication or exercise therapy. Lastly, we link the subtype-inflammation literature on to other known biological disturbances in depression, in particular metabolic dysregulation such as obesity and metabolic syndrome.