N100 and P50 Suppression in Schizophrenia and Bipolar Disorder: Effects of Time Block

Overview

Sensory gating, the process in which the brain filters out irrelevant stimuli, was assessed for N100 and P50, two evoked auditory potential waves appearing approximately 100 and 50 milliseconds, respectively, after the administration of the stimulus, using the paired auditory stimulus paradigm. Schizophrenic and bipolar patients tend to demonstrate difficulty with processes of sensory gating. This study was undertaken to evaluate whether responses in the sensory gating paradigm diminish during successive trial blocks in normal, schizoaffective, paranoid schizophrenic and bipolar disorder patients. N100 and P50 potentials were collected from individuals diagnosed with schizoaffective disorder (n = 34), paranoid schizophrenia (n = 31), bipolar I disorder (n = 31) and controls (n = 30) diagnosed using DSM-IV criteria and the Structured Clinical Interview for DSM-IV. N100 gating ratio, the amplitude of N100 to the second of two paired clicks divided by the response to the first, demonstrated a significant main effect for trial block. P50 gating ratios had a significant group by channel interaction. Peak-to-peak amplitude of N100 demonstrated a significant block by click interaction. Peak-to-peak amplitude of N100 was only significantly different during the first half of trials and not during the second half of trials. These results demonstrate the importance of examining the effect of trial blocks when comparing gating ratios and peak-to-peak amplitudes between patient groups. The gating ratios and peak differences can provide a biological marker for schizophrenia and bipolar disorder.

Competition history

• AJAS 2019 Category not listed

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