Affective processing in individuals with depressive symptoms: an ERP study

ABSTRACT Introduction: depression is a mood disorder characterised by negative mood and anhedonia that causes significant impairments to affected individuals. Given the significant burden of depression, identifying early indicators of the disorder has been suggested as a core priority. Altered affective processing has been identified as a potential indicator underlying the development and maintenance of the disorder. The elaboration of affective stimuli includes multiple stages (i.e., cue evaluation and engagement, anticipation, and elaboration); however, how each stage relates to depressive symptoms remains unexplored. Event-related potentials (ERPs) of the electroencephalographic (EEG) signal, thanks to their excellent temporal resolution, offer unique insights into the different stages of affective processing. Study aims: this study aimed to investigate the anticipation and processing of affective stimuli in individuals with different levels of depressive symptoms. Materials and methods: A sample of 42 (21 females) students from the University of Padua were recruited. An S1-S2 paradigm, a task in which an emotional picture (S2) is preceded by a cue (S1) anticipating its valence, was employed during an electroencephalographic (EEG) recording. Three ERPs reflecting different stages of emotional processing were assessed: the Cue-P300 (reflecting cue-evaluation and affective engagement), the Stimulus Preceding Negativity (SPN; reflecting outcome anticipation), and the Late Positive Potential (LPP; reflecting affective processing). Results and conclusions: Mixed-effect models showed that higher levels of depressive symptoms predicted a reduced LPP amplitude to pleasant, but not unpleasant, pictures. No other effects emerged regarding the Cue-P300 or the SPN. These results suggest that subclinical depressive symptoms might be characterized by blunted affective elaboration, rather than the anticipation, of pleasant stimuli. Taken together, the ERPs might be leveraged to enhance the early identification and the design of treatment protocols for depressive symptoms. Keywords: ERP; Depressive symptoms; affective elaboration.