A Comparative Study of Event-related Potential N400 between Anxious and Melancholic Depression

Background There are many subtypes of major depressive disorder (MDD) . Evidence about the differentiation of them is mostly based on symptomatological characteristics, but rarely by objective biological indicators. Objective To explore the differences in event-related potential (ERP) N400 between patients with different subtypes of depression, providing an objective electrophysiological basis for subtyping depression. Methods Two hundred and nine outpatients and inpatients who met the diagnostic criteria of MDD in Diagnostic and Statistical Manual of Mental Disorders, 5th Edition were selected from First Hospital of Shanxi Medical University from February 2019 to December 2021, including 78 with anxious depression (ASD+MD-) , 46 with melancholic depression (ASD-MD+) , 61 with anxious and melancholic depression (ASD+MD+) , and 24 with non-anxious and melancholic depression (ASD-MD-) subtyped using the 30-item Inventory of Depressive Symptomatology (IDS-30) and 17-item Hamilton Depression Rating Scale (HAMD-17) . Thirty-five community-living health volunteers were recruited as controls at the same time.The factor and total scores of the HAMD-17 and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) of all subjects were collected. And the latency and amplitude of N400 component of all subjects were collected by inducing N400 components through understanding ambiguous words at the end of sentences. Results (1) The total score and factor scores of HAMD-17 differed significantly across MDD subgroups and control group (P< 0.05) . The total score of HAMD-17 in each of the four MDD subgroups was much higher than that in control group (P0.05) .There were no significant differences in latency and amplitude of N400 component across different electrode sites (P>0.05) , and there were no interaction between no-depression or each of the four subtypes of MDD and electrode sites (P>0.05) . (4) The N400 amplitude value at Fz electrode was negatively correlated with the cognitive impairment factor score (r=-0.170, P=0.016) .The N400 amplitude value at Cz electrode was positively correlated with the block factor score (r=0.151, P=0.033) .The N400 amplitude valueat Pz electrode was positively correlated with the block factor score (r=0.174, P=0.014) .The N400 amplitude value of the Fz electrode was positively correlated with the immediate memory score (r=0.138, P=0.050) .The N400 latency value at Cz electrode was negatively correlated with the delayed memory score (r=-0.155, P=0.028) . Conclusion Extensive cognitive impairment was found in MDD patients, including impaired immediate memory, speech function, attention and delayed memory. ASD+MD+ and ASD+ MD-patients had more severe symptoms, and ASD+MD+ patients had the most severe cognitive impairment. N400 amplitude value was negatively correlated with cognitive impairment and positively correlated with block factor in MDD patients. But these patients demonstrated no impaired function of speech integration induced by ambiguous words at the end of sentences.