BackgroundCognitive impairment frequently accompanies first-episode major depressive disorder (MDD) in patients. Early detection and intervention for cognitive impairment can enhance the quality of life for individuals with depressive disorders. Impaired emotion recognition may serve as an initial manifestation of cognitive impairment in these patients. This study examines the characteristics of event-related potentials N170 and dysfunctional attitudinal questionnaire total scores, as well as each factor and their correlation, revealing characteristic electroencephalogram (EEG) changes associated with cognitive impairment in first-episode MDD patients. MethodA total of 88 patients experiencing first-episode MDD and 29 healthy volunteers from the same period participated in the study. They underwent event-related potential N170 measures to assess mood recognition function, the 17-item Hamilton depression scale (HAMD-17) to evaluate the severity of depressive disorder, and the Dysfunctional Attitudes Scales(DAS) to appraise cognitive function. ResultThe dysfunctional attitude questionnaire's total score and each factor score were higher in the MDD group compared to the healthy control (HC) group. The MDD group exhibited lower amplitudes than the HC group at CZ, PZ, POZ, P7, PO7, P8, and PO8 electrode points. A correlation was identified between the P7 and PO7 electrode points of the event-related potential N170 and cognitive function. LimitationThis study solely considered neutral face emotional stimuli and did not account for depressive disorder subtypes. ConclusionDifferences were observed between the MDD and HC groups in cognitive function and N170 amplitude in the central brain region (CZ, PZ, POZ), left posterior temporal region (P7), left occipitotemporal region (PO7), right posterior temporal region (P8), and right occipitotemporal region (PO8). Additionally, a correlation was found between N170 latency in the left posterior temporal region of the brain (P7) and the left occipitotemporal region (PO7) with cognitive function.