Questions under study: Prepulse inhibition (PPI) is the normal suppression of the startle reflex when the intense startling stimulus is preceded by a barely detectable prepulse. PPI has been proposed to reflect a measure of sensorimotor gating or filtering. Deficits in PPI has been found in schizophrenia in various prepulse conditions. The aim of this study was to investigate whether deficits in particular prepulse conditions relate to psychopathological syndromes.
Methods: Schizophrenia was subgrouped into patients with deficit and with nondeficit syndrome using the schedule of Kirkpatrick. Schizophrenia with deficit syndrome (N = 46), schizophrenia with nondeficit syndrome (N = 21), and controls (N = 44) were compared in an acoustic startle paradigm assessing PPI (30, 60, 120, 240 and 2000 ms interstimulus intervals). A mixed ANOVA was used to analyse the PPI-data.
Results: Schizophrenia with deficit syndrome showed a PPI-deficit in the 60 ms prepulse condition and a reduced facilitation in the 2000 ms prepulse condition, whereas PPI in patients with nondeficit syndrome was impaired in the 240 ms prepulse condition.
Conclusions: The different patterns of PPI in deficit and nondeficit patients appear to relate to the heterogeneity of schizophrenia. Thus, this study may explain the various findings in previous PPI studies in the field of schizophrenia.