Introduction Major depressive disorder (MDD) represents the leading cause of global disease burden, characterized by high prevalence, profound disability, and diagnostic challenges.1 Its clinical phenotype encompasses multiple dimensions—affective (sadness, emptiness), interest-related (loss of interest), cognitive (self-blame, helplessness), and neurovegetative (sleep/appetite disturbances)—reflecting substantial heterogeneity.2 Among these, anhedonia—defined as “markedly diminished interest...
