Affective processing in anhedonia: An ERP study

Background: Anhedonia, defined as a loss of pleasure towards appetitive stimuli, is a core symptom of depression and a vulnerability factor for its development. Prior research has demonstrated that anhedonia is associated with blunted emotional processing of appetitive stimuli. However, the precise relationship between the different stages of affective processing and anhedonia remains poorly understood. Event-related potentials (ERPs) offer a valuable tool for differentiating between distinct temporal stages of affective processing. Specifically, the Cue-P300 reflects cue-evaluation and allocation of attentional resources toward the expected emotional stimulus, the Stimulus Preceding Negativity (SPN) indicates affective anticipation, and the Late Positive Potential (LPP) represents motivated attention and elaboration of affective stimuli. Aim of the study: The objective of the present study was to disentangle the influence of anhedonia on the distinct stages of affective processing through the analysis of the ERP components Cue-P300, SPN and LPP. Materials and methods: Forty-five university students (31 females) with varying anhedonia levels, as assessed through the Snaith-Hamilton Pleasure Scale (SHAPS), and no current diagnosis of depression participated in the study. Participants underwent an S1-S2 paradigm, in which an image (S2) was preceded by a cue (S1) anticipating its valence (pleasant, neutral, unpleasant). The electroencephalography (EEG) was recorded to obtain ERPs related to the processes of interest (Cue-P300, SPN, and LPP). Linear mixed-effects models were used for statistical analysis, with a separate model computed for each ERP component of interest Results: The analyses yielded a significant main effect of Category for the SPN and LPP, which was further qualified by a significant Category × SHAPS interaction effect showing that higher anhedonia levels were associated with larger SPN and smaller LPP amplitudes specifically in response to pleasant images as compared to neutral ones. The Cue-P300 analysis revealed a significant main effect of Category, with a larger Cue-P300 amplitude for pleasant images compared to both neutral and unpleasant images. No significant Category × SHAPS interaction effect was found for the Cue-P300. Conclusion: These findings suggest a complex pattern of affective processing in non-clinical individuals with anhedonia, characterized by a rapid transition from increased anticipation to reduced elaboration of appetitive stimuli. Therefore, the present study elucidates how anhedonia influences the different stages of affective processing, further exploring the affective processing deficits linked to depression vulnerability.