Behavioral and electrophysiological analyses of self-referential neural processing in major depressive disorder

Cognitive theories suggest that patients with major depressive disorder (MDD) constantly negatively evaluate their self-referential information. Unlike Westerners with an independent self, self-representation is strongly influenced by cultural differences; the Chinese self may include others (interdependent self). This study uses a self-referential effect task combined with event-related potentials (ERP), and 34 patients with MDD and 54 healthy controls (HC) were asked to judge whether an adjective was suitable for describing the self, mother, or a public person, followed by an unexpected recognition task. They were required to judge whether a word was presented during the encoding phase. The results reveal that during the encoding phase, for both self- and mother-referential adjectives, patients with MDD endorsed fewer positive adjectives and more negative adjectives than the HCs. During the recognition phase, both groups showed a typical task effect (self = mother > other), while patients recognized more self-referential adjectives than the HCs. ERP data reveal that patients with MDD show larger P2 amplitudes during the encoding stage than healthy individuals. During the recognition phase, negative adjectives evoked larger P2 amplitudes in patients than in HCs under the self-referential condition. These findings shed important light on the information processes that may contribute to our understanding of depression and may offer implications for clinical interventions.