Sensorimotor gating and habituation of the startle response in the prodrome of schizophrenia

Patients with schizophrenia exhibit impairments in habituation and sensorimotor gating of the acoustic startle response (ASR). Animal data suggested that a deficit in prepulse inhibition (PPI) of the ASR, which is used as an operational measure for sensorimotor gating, is genetically determined. To test the assumption, that both gating and habituation are candidate endophenotypes of schizophrenia, we investigated startle reactivity, habituation and PPI of the ASR in 51 subjects with prodromal symptoms of schizophrenia, in 28 first episode schizophrenics and in 33 healthy volunteers. Subjects in early prodromal stages and unmedicated patients with first episode schizophrenia did show a PPI deficit, whereas antipsychotically treated subjects showed almost normal PPI. In contrast, startle reactivity and habituation decreased with proceeding of the illness (controls > early prodromal group > late prodromal group > first episode schizophrenics). Antipsychotic medication improved also startle reactivity and habituation in schizophrenic patients. Our findings suggest that PPI is possibly an endophenotype of schizophrenia, because it occurs already at an early stage of the prodromal phase, whereas startle reactivity and habituation deficits are rather symptoms of schizophrenia, because they are getting worse with process of the illness. Funded by the German Federal Ministry for Education and Research BMBF (grant 01-GI–9934).