Short-Term Prospective Comparison of Prepulse Inhibition between Schizophrenic Patients and Healthy Controls

Introduction: The prepulse inhibition (PP1) of acoustic startle reflex is impaired in schizophrenic individuals compared to normal controls, and has been suggested to be a biomarker for sensorimotor gating. In fact, some cross-sectional studies suggest a different type of effect on PPI changes depending on the kind of antipsychotic treatment but few prospective studies have been conducted to investigate the short-term course of PPI alterations during the first few weeks of treatment. This study aimed to investigate schizophrenic subjects and controls over 4 weeks to analyze the course of PPI changes between groups at baseline and during follow-up, to determine whether potential PPI alterations are influenced by type of antipsychotic medication and whether these alterations are accompanied by changes in psychopathology. Methods: 39 schizophrenic patients and 39 controls were enrolled into this open prospective trial. Acoustic startle response (PPI) measurements and clinical (PANSS) performance were obtained shortly after admission and every 14 days for a 4-week follow-up period (T1 to T3). Results: Patients were treated with first and/or second generation antipsychotics in an open-label design. At baseline (T1) significant deficits were detected between schizophrenic subjects and controls for several PPI conditions. Neither was a relationship between type of antipsychotic treatment and PPI measures detected at baseline and during follow-up, nor was any association with PANSS psychopathology found. Discussion: The results of our study confirm previous research on PPI deficits in schizophrenic subjects. As with previous prospective PPI studies in schizophrenic subjects, initial PPI deficits were not observed during the follow-up period, independent of the kind of antipsychotic treatment and severity of psychopathology. These findings may indicate that PPI serves as a biological marker of schizophrenic psychosis and sensorimotor gating independent of type of antipsychotic administered or severity of psychotic symptoms.