Neuroleptic effects on P50 sensory gating in patients with first-episode never-medicated schizophrenia
ABSTRACT Sensory gating deficit, as reflected by P50 suppression, has been demonstrated in schizophrenia. Despite extensive evidence of the irreversible effects of typical neuroleptics on this deficit, recent studies of atypical neuroleptics have produced inconsistent findings on the reversibility of P50 suppression in schizophrenia. As the majority of these studies were limited by either their cross-sectional design or the recruitment of patients on multiple medications, the current study was designed to examine the effects of different neuroleptic medications on the P50 sensory gating index in patients with first-episode, never-medicated schizophrenia. P50-evoked potential recordings were obtained from 62 normal controls when they entered the study and from 65 patients with first-episode, never-medicated schizophrenia at baseline and after six weeks of different neuroleptic treatments (sulpiride [n=24], risperidone [n=24] and clozapine [n=17]). The first-episode, never-medicated schizophrenia patients had impaired sensory gating relative to the normal controls (mean=94.19% [SD=61.31%] versus mean=41.22% [SD=33.82%]). The test amplitude S2 was significantly higher in the schizophrenia patients than in the normal controls. The conditioning amplitude S1 and the positive symptom scores were related to the P50 gating ratios in schizophrenia at baseline. There was no change in P50 sensory gating (P>0.10) and a significant improvement in the clinical ratings (P>0.10) after six-week neuroleptic treatment for schizophrenia. P50 sensory gating was not significant for the patients who received sulpiride, risperidone or clozapine at baseline (F=1.074, df=2, 62, P=0.348) or at endpoint (F=0.441, df=2, 62, p=0.646). Our findings indicate that there is P50 sensory gating impairment in first-episode, never-medicated schizophrenia and that treatment with typical and atypical antipsychotics has no significant impact on such gating in this illness.
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ABSTRACT: Event-related potentials (ERPs) are objective electrophysiological indicators that can be used to assess cognitive processes in the human brain. Psychiatric researchers in China have applied this method to study schizophrenia since the early 1980s. ERP measures used in the study of schizophrenia include contingent negative variation (CNV), P300, mismatch negativity (MMN), error-related negativity (ERN) and auditory P50 inhibition. This review summarizes the main findings of ERP research in patients with schizophrenia reported by Chinese investigators.04/2012; 24(2):67-75. DOI:10.3969/j.issn.1002-0829.2012.02.001
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ABSTRACT: Evoked and induced event-related neural oscillations have recently been proposed as a key mechanism supporting higher-order cognition. Cognitive decay and abnormal electromagnetic sensory gating reliably distinguish schizophrenia (SZ) patients and healthy individuals, demonstrated in chronic (CHR) and first-admission (FA) patients. Not yet determined is whether altered event-related modulation of oscillatory activity is manifested at early stages of SZ, thus reflects and perhaps embodies the development of psychopathology, and provides a mechanism for the gating deficit. The present study compared behavioral and functional brain measures in CHR and FA samples. Cognitive test performance (MATRICS Consortium Cognitive Battery, MCCB), neuromagnetic event-related fields (M50 gating ratio), and oscillatory dynamics (evoked and induced modulation of 8-12Hz alpha) during a paired-click task were assessed in 35 CHR and 31 FA patients meeting the criteria for ICD-10 diagnoses of schizophrenia as well as 28 healthy comparison subjects (HC). Both patient groups displayed poorer cognitive performance, higher M50 ratio (poorer sensory gating), and less induced modulation of alpha activity than did HC. Induced alpha power decrease in bilateral posterior regions varied with M50 ratio in HC but not SZ, whereas orbitofrontal alpha power decrease was related to M50 ratio in SZ but not HC. Results suggest disruption of oscillatory dynamics at early stages of illness, which may contribute to deficient information sampling, memory updating, and higher cognitive functioning.Schizophrenia Research 06/2014; DOI:10.1016/j.schres.2014.05.012 · 4.43 Impact Factor
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ABSTRACT: Background The effects of smoking on cognitive performance have long been studied, with mixed results. P50 sensory gating has been used as endophenotype for studying nicotinic systems genetics, and P50 gating deficits have been reported to be a sensitive biomarker for cognitive impairment in schizophrenia. This study examined the inter-relationship between P50 suppression, cognitive function, and smoking in a healthy Han Chinese population, which has not been reported before. Methods We recruited 82 healthy male subjects, including 48 smokers and 34 non-smokers who were matched for age and education. The authors measured P50 sensory gating and administered the Chinese-language version of the MATRICS Consensus Cognitive battery (MCCB) and Stroop tests. Results The results showed that the smokers scored lower than nonsmokers on the MCCB Brief Visuospatial Memory Test (BVMT) index and the STROOP test. Furthermore, the MCCB total score was negatively associated with number of cigarettes smoked per day in the smoker group. However, P50 sensory gating was not associated with either smoking status or any cognitive performance. Conclusions Our results show that smoking is associated with cognitive impairment, but not with P50 sensory gating.Drug and Alcohol Dependence 10/2014; 143. DOI:10.1016/j.drugalcdep.2014.06.045 · 3.28 Impact Factor