A Clinic Study On Auditory Sensory Gating Potential P50 In The First-episode Schizophrenia

Objective: Sensory gating is the ability of neuronal networks within the human brain to transmitonly a small part of incoming information and to filter out irrelevant stimuli. This mechanism isbelieved to be important for normal brain function as it protects the brain from informationoverflow. The sensory gating impairment may lead to sensory overload, attention deficit,cognition fragmentation and information processing disturbance. P50 is an electroencephalogramevent-related potential waveform used to assess sensory gating. There is a large body of evidenceto suggest that schizophrenia and their unaffected first degree relatives have P50 sensory gatingdeficits, but there is little available data to address what illness components and whetherantipsychotics effects are associated with P50. The aim of this study is to prove the sensorygating P50 (SG P50) deficit in the schizophrenics and their first-degree relatives; to evaluateinfluences of antipsychotics on SG P50; and to show the association for SG P50 with clinicalsymptoms. Furthermore, to approach whether or not that the index of SG P50 were aphenotype marker for categorization diagnosis and generation study.Methods: (1) Subjects: 62 first episode schizophrenics (Sch group), 44 schizophrenicunaffected first degree relatives (FR) and 51 normal controls (NC). The schizophrenics meet thediagnostic criterion of schizophrenia and schizoid disorder, and are neuroleptic-naive beforeadmission (PANSS≥60). Organic disease of brain and mental disorders associated with physicaldiseases and substances dependence have been excluded.(2) steps: All the subjects were tested about their SG P50 when admission. The Sch group wasevaluated with positive and negative syndrome scale (PANSS) and Wisconsin Card Sorting Test(WCST) when being admitted to the group and 6 weeks after treatment. And the Sch group wastested about SG P50 again the second 6 weeks after treatment.(3) Tools: The machine for testing brain evoked potential using to record SG P50 is fullyfunctional, digital, 40 leads, EBNeuro Sirius BB BE and made in Italy. PANSS of Chineseversion is used to evaluate the psychiatric symptoms of patients. WCST software system isadopted to evaluate the WCST of patients which is from Changsha Ririxin Industry Limited.(4) Statistical method: The SPSS 13.0 statistical package is adopted to process the data, mainlyincluding analysis of variance (ANOVA), t-test, Kruskal Wallis Test and spearman correlation analysis.Result: (1) The S1 amplitude, S1 and S2 latencies were no significantly different for Sch group,FR group and NC groupe. The S2 amplitude and S2/S1 ratio of Sch group and FR group werehigher than those of NC group (p＜0.05). The S2/S1≥0.5 persentage in Sch group, FR groupand NC group is 68%,64% and 32% respectively (p＜0.05). The coefficients correlation ofS2/S1 and S1 amplitude had statistical significance in the Sch group (p＜0.05,r=-0.39), and sothe S2/S1 and S2 amplitude (p＜0.05,r=0.74).(2) There were no significantly different for the index of SG P50 between pre-and after-6-week antipsychotic treatment (all p＜0.05).(3) The index of SG P50 were no significantly different for the comparison of patientsreceiving sulpride (18 cases), clozapine (10 cases) and risperidone (12 cases) treatments.(4) The P50 index didn't differ significantly in sex for Sch and NC groups.(5) The total scores of PANSS, the scores of positive syndrome factor and negative syndromefactor were difference significantly between pre-and after-antipsychotic treatment (all p＜0.01).(6) Spearman correlation analysis: None of the coefficients correlation of S1 and S2 waveamplitude, S2/S1, the total scores of PANSS scale, and the scores of positive symptom factorand negative symptom factor has statistical significance in Sch group; the coefficients correlationof S2/S1 and the total scores of PANSS in negative symptom group have statistical significanceeither between pre-and after-treatment(p＜0.05); the coefficients correlation of S1 waveamplitude and the three factors of PANSS scale have statistical significance after treatment (p＜0.05), And so the S2/S1 and negative syndrome factor(p＜0.05). The coefficients correlation ofS2/S1 and the scores of positive symptoms factor have statistical significance in the non-negativesubgroups (p＜0.05) before treatment. But the correlation disappeared after treatment.(7) There was significantly different between S1 amplitude of SG PS0 and the completionclassification number of WCST in Sch group.Conclusion: 1.The first-episode schizophrenics and their unaffected first-degree relatives havedeficit in SG PS0, which reflects the abnormality of central inhibition in the patients and theirrelatives.2. The antipsychotics medications did not effect P50 sensory gating for 6-weeks treatment. 3. The patients receiving sulpiride, clozapine and risperidone did not significantly differ fromone another in their SG P50.4. There were no difference on SG P50 for Sex.5. The P50 sensory gating was independently of clinical symptom of patient at different stages inpre-and after-treatment. The scores of PANSS and the SG P50 of schizophrenics who havemainly negative symptoms, reflecting abnormal cognitive function of schizophrenics. The non-negative subgroups before treatment determine the severity of the disease of schizophrenics, whodisplay mainly positive symptoms, which correlates with the gating function. The correlationdisappeared after treatment. There is some correlation between the indexes of SG P50 and theclinical symptoms.6. The S1 amplitude of SG P50 correlates with the completion classification number of WCST inSch group suggests the frontal lobe participate the regulation of SG function and the lesion offrontal lobe related with selective attention deficiting.In general, The first-episode schizophrenics and their unaffected first-degree relatives havedeficit in SG P50, which reflects the abnormality of central inhibition. The frontal lobe parti-cipate the regulation of SG function. The P50 sensory gating was independently of clinicalsymptom of patient and antipsychotic treatment has no effected on it. SG P50 is a stablephenotype marker and maybe acts a biological trait for categorization diagnosis and generationstudy in schizophrenia.