Recent Change in Anhedonia, Major Depression and Low-Grade Inflammation: Dangerous Liaisons? A Study Based on a Cohort Referred for Polysomnography

<i>Background and Objectives:</i> Anhedonia is a core symptom of major depressive disorder (MDD) and worsens its prognosis. Inflammation has been associated with MDD, contributing to the severity of this pathology despite no clear clinical guidance on whether it should be integrated into the diagnosis or treatment of the MDD symptomatology. Notably, the neural basis of anhedonia is associated with alterations in the reward neural circuit, where inflammation may also interfere. In this study, we investigate whether recent change in anhedonia was associated with low-grade inflammation (defined as C-Reactive Protein levels between 3 and 10 mg/L) in MDD subjects. <i>Materials and Methods:</i> A retrospective study was conducted on 496 MDD subjects and drawn from the database of the sleep laboratory. Recent change in anhedonia was assessed via the Anhedonia Subscale of the 21-items Beck Depression Inventory (BDI-II), with scores > 3 indicating its presence. Recent change in anhedonia was defined as the recent onset or worsening of anhedonia complaints within the past 2 weeks. Anxiety and sleep disturbances were also evaluated and inflammatory status was determined based on CRP levels. <i>Results:</i> After adjusting for the main confounding factors, the multivariate logistic regression confirms a clear association between recent change in anhedonia and low-grade inflammation, thereby contributing to a detrimental context underlying the symptom. <i>Conclusions:</i> A better understanding of anhedonia in the context of inflammation could enable treatment adjustments and improve the poor prognosis of anhedonia-type depression.