Semantic processing of emotional words in depression and schizophrenia

Major depressive disorder is associated with dysfunction in brain regions involved in language and emotion processing. Despite evidence of emotion processing biases in depression, neurophysiological evidence of language dysfunction for emotional words in depression has been inconsistent. This series of three studies evaluated whether depressed individuals exhibited abnormal semantic processing of emotionally-valenced words. During the passive viewing of sentences with mood congruent and incongruent sentence endings, the N400 component of the event-related brain potential was measured in patients with depression, dysthymia, or schizophrenia and in healthy controls. In each study, results revealed normal semantic processing in depression. That is, N400 was similar for both mood-incongruent (positive and neutral) endings and mood-congruent (negative) endings. In contrast, the small sample of individuals with schizophrenia exhibited a significantly exaggerated N400 for negative word endings compared to the depressed and healthy control groups. These data suggest anomalies in semantic network interactions with emotion processing in schizophrenia.