Anhedonia and its intervention in depressive adults: New developments based on Research Domain Criteria (RDoC) in mental illnesses

Anhedonia, as one of the core symptoms of depression, is of great significance for the diagnosis and treatment of depression. Traditionally, anhedonia has been referred to as "loss of pleasure", while the recent research emphasizes that anhedonia is a complex and multidimensional construct based on reward processing impairment. Exploring different manifestations of anhedonia and developing the corresponding interventions have become indispensable in the current research of depression. Based on the positive valence system of the Research Domain Criteria (RDoC), this paper firstly demonstrates that the anhedonia of depressive adults are mainly characterized by the impairments in anticipatory pleasure, incentive motivation/effort, and reward learning based on subjective rating, behavioral, and neurophysiological evidences, while the existing evidences for the consummatory anhedonia of depression are inconsistent. Additionally, we introduce the vulnerability–stress model, as the mainstream theory of anhedonia in depression, and also emphasize the role of dopamine system abnormalities and altered brain structures or functional networks underpinning reward processing in the pathogenesis of anhedonia. Furthermore, to reinstate reward processing in depressed adults, various effective interventions for anhedonia have been developed, including direct psychosocial interventions, indirect working memory training, and real-time neurofeedback training with functional magnetic resonance imaging (fMRI). Future research needs to deeply investigate the role of stress and gene polymorphisms in the etiology and mechanism of anhedonia in depression. Besides, more attention should be paid to social anhedonia in depressed individuals. And we also emphasize the need to further promote translational studies on the clinical interventions of anhedonia.