| Objective:To observe the characteristics of the visual event-related potentials P300ofschizophrenic patients, and the changes of both its amplitudes and latencies before andafter modified electroconvulsive therapy (MECT), and evaluate the effect of MECTon cognitive function of patients with schizophrenia.Methods:23inpatients with schizophrenia referred for MECT constituted the experimentalgroup (MECT group).22age, gender, education level and handedness matchedinpatients with schizophrenia purely treated with antipsychotic as Drug group and24healthy subjects as normal control group. An oddball paradigm visual event-relatedpotential P300were measured on all the subjects one day before MECT, and at theday after last therapy and the end of1,2,4,8weeks after MECT or correspondingtime points (respectively defined as measurement time point1,2,3,4,5,6). Subjectsof MECT group and Drug group were also scored with Positive and NegativeSyndrome Scale (PANSS) on all the6measurement times to evaluate the efficacy oftreatment. Chinese Wechsler Memory Scale-revised (WMS-RC) was tested at measurement time points1,2,6to compare the subjects’ memory level. Three aspectsof data were compared:1. Treatment efficiency between MECT group and Drug group,and2. differences among three groups on averaged reaction time and correct responserate to the target stimuli, and3. differences among three groups on the averageamplitudes and latencies of visual P300at the electrode sites of Fz, Cz and Pz.Results:1. Treatment efficiency comparison: According to the PANSS, treatment efficacyof MECT was82.61%corresponds to81.82%of antipsychotic, which showed nosignificant difference (χ~2=1.01，P=0.799). MECT group had lower PANSS Positive,General psychopathology subscores and Total score than Drug group on the end ofMECT (t(43)=5.286、2.260、2.406, P=0.000、0.029、0.021), whereas a higher PANSSNegative subscore (t(43)=7.608，P=0.000). To the end of follow-up, there was nosignificant difference between two groups on all subscores and total score.2.Behavioral data comparison:①ANOVA showed no significant differenceamong three groups on the average reaction time to target stimuli in all6tests(F(2,66)=0.288、2.121、0.607、0.504、0.439、0.380，P=0.751、0.128、0.548、0.607、0.647、0.685). Subjects of MECT group had the longest reaction time in the secondmeasurement，and there was no significant difference with Drug group（P=0.255）.②ANOVA showed significant differences among three groups on the correct responserates to the target stimuli in all6tests (F(2,66)=8.245、11.949、3.999、3.307、4.531、3.653，P=0.001、0.000、0.023、0.043、0.014、0.031). Both MECT group and Druggroup had lower correct response rates than normal control group. MECT groupshowed lowest correct response rate in the second measurement, which displayedsignificant difference with Drug group and normal control group (P=0.003、0.000).3.ERP data comparison: Define group as between-subject factor, electrode sites andtest time points as within-subject factor,①a repeated measures ANOVA revealed a significant group, electrode sites, measurement time main effect and a significantelectrode sites×group, measurement time×group and electrode sites×measurementtime interaction effect for average P300amplitudes (for group: F=15.887, P=0.000;for electrode sites: F（2,66）=442.564，P=0.000; for measurement time: F（5,63）=80.722,P=0.000; for electrode sites×group: F（4,64）=14.692, P=0.000; for measurementtime×group: F（10,58）=28.406, P=0.000; for electrode sites×measurement time: F（10,58）=3.549, P=0.004).②A repeated measures ANOVA also revealed a significant group,electrode sites, measurement time main effect and a significant measurementtime×group interaction effect for average P300latencies (for group: F（2,66）=4.035,P=0.022; for electrode sites: F（2,66）=9.858, P=0.002; for measurement time: F（5,63）=116.745, P=0.000; for measurement time×group: F（10,58）=40.318, P=0.000).Conclusion:1. The visual P300amplitudes decreased and latencies prolonged in patients withschizophrenia, which supports that they exit cognitive function deficits. The P300amplitude and latency improved after treatment, which provides evidence that bothvisual P300amplitude and latency were state markers of schizophrenia.2. Patients with schizophrenia displayed short-term visual P300latency delaysafter MECT and the amplitude increased. As time went on, the P300latency reducedand showed almost same changing trends with Drug group. The results indicate thatthough MECT can cause impairment on cognitive function, it might also amelioratecognitive function regarding the long-term efficacy. |
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