Medication status affects the relationship of symptoms to prepulse inhibition of acoustic startle in schizophrenia

Inhibition of the acoustic startle response by a smaller preliminary nonstartling stimulus is termed prepulse inhibition (PPI). Schizophrenia patients have impairments in PPI that may not fully normalize even when they are clinically stable on medication, particularly typical antipsychotics. There is evidence that more severe symptoms are associated with more severe PPI abnormalities, but the effect of antipsychotics on this relationship is not clear. Seventy-three male schizophrenia patients underwent acoustic startle and PPI testing. Symptom ratings were performed using the Brief Psychiatric Rating Scale (BPRS) and its subscales. Fifty-two subjects were treated with antipsychotic medication at time of testing; 21 were unmedicated. For all subjects, PPI was negatively correlated with the BPRS psychological discomfort subscale but not with BPRS total symptoms, BPRS positive symptoms or BPRS negative symptoms. For medicated subjects analyzed separately, there were no correlations with BPRS total scores or any subscales. For the unmedicated subjects analyzed separately, there were significant correlations of lower PPI with greater severity of BPRS total symptoms, positive symptoms and the psychological discomfort subscale. These data indicate that more severe symptoms are associated with lower PPI, but that medication status is an important factor in the relationship between symptom severity and sensorimotor gating.