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-S-2 amplitude and increased amplitude ratio S-2/S-1 (both P < 0.05). In the control group, the smokers had a tendency of increase in P50-S-2 amplitude (P > 0.05) and shorter P50-S-2 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-S-1 amplitude, shorter P50-S-2 latency, and higher amplitude ratio S-2/S-1 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.