P50 sensory gating deficit is a common marker of vulnerability to bipolar disorder and schizophrenia.

OBJECTIVE

P50 gating in schizophrenia has contributed much to our understanding of the pathophysiology of the illness. We examined euthymic bipolar patients to determine if they also have a P50 gating deficit.

METHOD: P50 gating was measured in 81 euthymic bipolar patients (50 with a lifetime history of psychotic symptoms), 92 stable schizophrenic patients, and 67 control subjects.

RESULTS

P50 gating was significantly lower in control subjects than in bipolar patients with a lifetime history of psychosis (P = 0.001) and schizophrenic patients (P = 0.0001). In all patient groups, the percentage of patients with P50 gating was higher than in the control group (chi(2) = 30.596; P < 0.0001). There was no statistically significant correlation between P50 gating and other clinical variables.

CONCLUSION

Our data suggest that P50 gating deficit is a neurobiological marker that is present in stable schizophrenic patients and euthymic bipolar patients.