The Central Executive System In Working Memory In First-episode Schizophrenia Patient:an ERPs Study

Objective:(1) to compare differences between normal people and first-episode drug-naive schizophrenia patients in behavioral performance of neuropsychological tests which are related to central executive function of working memory;(2) to compare differences between normal people and first-episode drug-naive schizophrenia patients in ERP components and their brain distribution under three conditions of working memory task, and to further explore the characteristic of neural mechanism in central executive functional impairment of patients with schizophrenia.Methods:By using neuropsychological tests such as joint category fluency test, Paced Auditory Serial Addition Test (PASAT), trail making test (TMT), Stroop test, Wiscosin Cards Sorting Test (WCST-64), dynamic memory task, to evaluate the central executive function in normal people (n=28) and first-episode patients with schizophrenia (n=50). Positive and negative symptoms scale (PANSS) were also used to assess the psychiatric symptoms for patients. Normal subjects (n=25) and first-episode patients with schizophrenia (n=42) completed three conditions with variable parameters of the Sternberg (SIRP) working memory task. Behavioral data and EEG data were recorded at the same time. After offline data processing, the two groups were compared under rehearsal condition, low executive condition and high executive condition for behavioral performance and ERP component differences.Results:(1) Neuropsychological tests showed that, no significant differences existed in false response of TMT between first-episode drug-naive patients with schizophrenia and normal controls (P>0.05), but for all the other test indexes, the patient group had significantly lower level of performance than the control group (P<0.05).(2) ERP results:1、 behavioral results found that first-episode drug-naive patients with schizophrenia showed longer reaction time(F(1,65)=28.68, P=0.000) and lower accuracy (F(1,65)=20.796, P=0.000) than the controls under three conditions. For both the normal group and the patient group, significant differences exist in reaction time and accuracy between low executive condition and rehearsal condition, as well as low and high executive condition. But there exists no significant differences between rehearsal condition and high executive condition.2、ERP component results:three tasks with different levels of memory load all induced obvious P3, P1, N1and P2composition.(1) P3:the patient group showed significantly lower amplitude than normal group (F(1,65)=7.734, P=0.007),mostly under low executive condition (F(1,65)=19.836, P=0.000); But there exists no significant differences between patient group and normal group under rehearsal condition (F(1,65)=2.084, P=0.154)and high executive condition (F(1,65)=2.338, P=0.131).for the normal group, we found that P3amplitude was significantly higher under low executive condition than rehearsal condition (P=0.000) and high executive condition (P=0.000), but there exists no significant differences between rehearsal condition and high executive condition; latency analysis did not find any significant effect (F(1,65)=0.549, P=0.461).(2) For P1, between-group results found that the patient group showed significantly lower amplitude than normal group (F(1,65)=3.194, P=0.079); Latency analysis also found significant effect (F(1,65)=11.599, P=0.001).(3)For N1, first-episode schizophrenia showed lower amplitude than normal group(F(1,65)=4.393, P=0.040),but there exists no significant differences between patient group and normal group (F(1,65)=0.682, P=0.412).(4) P2:between-group analysis found that first-episode schizophrenia did not show decreased P2amplitude (F(1,65)=0.196, P=0.660); Latency analysis found that:the patient group showed increased P2latency (F(1,65)=5.885, P=0.018).Conclusions:(1) first-episode drug-naive patients with schizophrenia have deficiencies in various components of central executive function in working memory;(2) first-episode drug-naive patients with schizophrenia show significant differences in P3, P1, N1and P2composition induced by working memory task compared to normal controls, suggest that people with first-episode schizophrenia have defective functions in early visual encoding, background refreshing,working memory capacity and selective attention.