A meta-analysis of the late positive potential for assessing affective processing in depression and depression vulnerability

Depression and conditions conferring vulnerability to depression are thought to involve disruptions in emotional processing, yet the specific patterns and underlying neural mechanisms of these alterations remain unclear. To investigate emotional processing, studies often rely on tasks involving the viewing of standardized emotional visual stimuli, which elicit a range of psychophysiological responses. In this context, the late positive potential (LPP), an event-related potential reflecting motivated attention and emotional engagement, has emerged as a promising biomarker of emotional processing and has been applied in the study of depression. This preregistered meta-analysis quantitatively synthesized 23 studies (N = 2190) comparing LPP amplitudes to emotional visual stimuli in individuals with depressive symptoms, remitted depression, or familial risk, relative to controls. Across all stimulus categories, the whole sample of individuals with depressive symptoms and at-risk groups exhibited significantly reduced LPP, indicating a potential attenuated engagement with visual stimuli. Moderator analyses indicated that this pattern was not uniform across populations. In adults, reduced LPP amplitudes were evident for emotional but not neutral stimuli, whereas findings in developmental samples were heterogeneous and underpowered. Importantly, effects in at-risk populations were inconsistent and based on a limited number of studies, warranting cautious interpretation. Within-group analyses (11 studies; N = 1154) confirmed preserved affective modulation across samples, with larger LPPs to pleasant and unpleasant versus neutral stimuli. Overall, findings partly support the emotion context insensitivity hypothesis, suggesting a generalized attenuation of emotional processing in adults with depression or at-risk.