Disruption of sensory gating by moderate alcohol doses.

RATIONALE: Evidence from a growing body of literature suggests that alcohol, even at moderate-dose levels, disrupts the ability to ignore distractors. However, little work has been done to elucidate the neural processes underlying this deficit.
OBJECTIVE: The present study was conducted to determine if low-to-moderate alcohol doses affect sensory gating, an electrophysiological phenomenon believed to reflect the pre-attentive filtering of irrelevant sensory information.
METHODS: Sixty social drinkers were administered one of three doses intended to produce breath alcohol concentrations of 0.0% (placebo), 0.04% (i.e., low dose), and 0.065% (i.e., moderate dose). A paired-click paradigm consisting of 100 pairs of identical tones (S1 and S2) was used to assess sensory gating. Amplitudes of P50, N100, and P200 auditory evoked potentials (AEPs) were used to calculate gating difference (S1-S2) and ratio (S2/S1) scores.
RESULTS: The moderate alcohol dose significantly decreased P50 and N100 gating relative to placebo. Comparisons between the difference and ratio scores helped characterize the gating mechanisms affected at these stages of information processing. Alcohol did not alter P200 sensory gating.
CONCLUSIONS: These data suggest that alcohol disrupts pre-attentional sensory-filtering processes at breath alcohol concentrations (BrACs) below the current 0.08% legal limit. Future studies should perform a combined assessment of sensory gating and selective attention to better understand the relationship between these two alcohol-induced deficits.