Differences in P50 and prepulse inhibition of the startle reflex between male smokers and non-smokers with first episode schizophrenia without medical treatment

Backgorund Nicotine may improve schizophrenia patient＇s cognitive deficit symptoms.This study was to explore the chronic effects of smoking on prepulse inhibition of the startle reflex （PPI） and P50 in the patients with first-episode schizophrenia （FES）.Methods The event-related potentials （ERP） recording and analysis instrument made by Brain Products,Germany,was used to detect PPI and P50 in 49 male FES patients （FES group,n=21 for smokers and n=28 for non-smokers） and 43 normal male controls （control group,n=19 for smokers and n=24 for non-smokers）.Results Compared with normal controls,the FES group had prolonged PPI latency when elicited by single stronger stimulus （P ＜0.05）; the FES group had prolonged PPI latency and increased PPI amplitude （P ＜0.05,0.01） when elicited by weak and strong stimuli.The FES group had lower PPI inhibition rate than normal controls （P ＜0.05）.Compared with normal controls,the FES group had increased P50-S2 amplitude and increased amplitude ratio S2/S1 （both P ＜0.05）.In the control group,the smokers had a tendency of increase in P50-S2 amplitude （P ＞0.05） and shorter P50-S2 latency （P ＜0.05） than the non-smokers.The smokers had higher PPI amplitude than the non-smokers （P ＜0.05）.In the FES group,the smokers had higher P50-S1 amplitude,shorter P50-S2 latency,and higher amplitude ratio S2/S1 than the non-smokers （P ＜0.05,0.01）.The smokers had higher PPI amplitude than the non-smokers （P ＜0.05）.Conclusions There is obvious PPI and P50 deficits in schizophrenic patients.However,these deficits are relatively preserved in the smokers compared with the non-smokers,which suggests that long-term smoking might partially improve the sensory gating in schizophrenic patients.Whether this conclusion can be deduced to female patients requires further follow-ups.

P50 auditory sensory gating in first onset schizophrenics and normal healthy adults

The aim of this research was to investigate the variations of P50 auditory sensory gating(P50)in normal healthy adults and the first onset schizophrenics.By using the American Nicolet Bravo electromyography/evoked potential(EMG/EP)system,P50 was measured with conditioning-testing paradigm(paired-click stimuli S1 and S2 were used)in 58 first onset schizophrenics and 108 healthy adults,and the Positive and Negative Syndrome Scale(PANSS)was applied.The following three conclusions have been reached.(1)In normal control(NC)group,measured from central,anterior and posterior zone(Cz,Fz and Pz respectively),there were no statistical differences(P>0.05)between S1 and S2 evoked P50 peak latencies(S1-P50 and S2-P50);the ampli-tudes of S2-P50[(2.2P1.4),(2.3P1.5)and(2.1P1.4)μV respectively]reduced significantly as compared with S1-P50[(5.6P3.3),(5.6P3.9)and(4.9P2.8)μV respectively](P<0.01);the S2/S1 ration,S1-S2 difference,and 100(1-S2/S1)had no statistical differences(P>0.05).(2)Compared with NC,the schizophrenic group significantly showed lower S1-P50 amplitudes(P<0.01,except at Pz in whichZ=2.030,P=0.042),higher S2-P50 amplitudes,higher S2/S1 ratio,lower S1-S2 difference,and more decreased 100(1-S2/S1)(P<0.01)at Cz,Fz and Pz.(3)No significant correlations were found among S2/S1 ratio,S1-S2,100(1-S2/S1)of sen-sory gating and PANSS(P>0.05)in schizophrenic group.The first onset schizophrenics had sensory gating deficits,which could be quantified by P50.