Symptom correlates of prepulse inhibition deficits in male schizophrenic patients

Objective: Information processing, inhibitory, and gating deficits in human and animal model studies of schizophrenia are demonstrated by using prepul se inhibition of the startle reflex. Prepulse inhibition deficits in schizo phrenic patients correlate with core cognitive symptoms, such as thought di sorder and distractibility, but their relationship to positive and negative symptoms of schizophrenia is less clear. Method: Fifty-one male schizophre nic patients and 26 male normal comparison subjects were tested for prepuls e inhibition of the eyeblink component of the startle reflex measured by el ectromyogram recording. Startling stimuli (118 dB) were presented alone (pu lse only) or were preceded 60 msec by discrete prepulse stimuli of 2, 4, 8, or 16 dB above the background 70-dB noise level. In addition, patients wer e assessed for demographic variables, generalized symptoms (Brief Psychiatr ic Rating Scale), and positive and negative symptoms. Results: Schizophreni c and comparison groups differed significantly in the amount of prepulse in hibition produced by the 16-dB prepulse, with schizophrenic patients showin g the expected deficient prepulse inhibition. Latency of the eyeblink respo nse was generally slower for the schizophrenic patients, but the prepulse-i nduced latency facilitation for schizophrenic patients and comparison subje cts did not differ significantly. The pattern of prepulse inhibition defici ts in schizophrenic patients remained, with age and education controlled, i n an analysis of covariance and subgroup matching. Deficient prepulse inhib ition correlated with both positive and negative symptoms of schizophrenia. Conclusions: Under these experimental conditions, schizophrenia-linked def icits in prepulse inhibition detected with a relatively strong prepulse are correlated with both positive and negative symptoms of schizophrenia. The level of correlation, while significant in this cohort, is not as robust as that in previous reports linking prepulse inhibition deficits with other m easures, such as thought disorder. Future work should probably focus on the relationship of prepulse inhibition deficits to measures such as thought d isorder rather than positive and negative symptoms.