The relationship of N2 and P3 to inhibitory processing of social drinkers in a Go/NoGo task.

The aim of this study was to investigate links between the N2 and P3 NoGo ERP components in a visual Go/NoGo paradigm and inhibition in social drinkers. Forty participants were divided into three groups on the basis of their level of alcohol consumption, with two extreme groups, Light and Heavy, each with 13 subjects, selected for investigation. While impaired control over drinking was found in the Heavy group, there were no group differences in anxiety, depression, or locus of control. The Go N2 was slightly smaller centrally and in the midline for the Heavy compared to the Light group, but the Go P3 showed no group differences. The NoGo N2 was slightly smaller centrally, and the NoGo P3 was globally much smaller, in the Heavy group. Only the NoGo P3 reduction was correlated with alcohol consumption. That is, the NoGo P3 was the ERP component reflecting heavy social drinking. However, this could not be considered a marker of inhibition deficit, as the groups had similar performance levels in the task. Further consideration of the literature indicated that this is generally compatible with performance results in other studies that have attributed NoGo P3 differences to inhibition deficits, casting doubt on that interpretation. An alternative interpretation in terms of the orienting reflex (OR) is offered. This suggests that individuals with impairments in basic aspects of reflexive OR functioning may be prone to risk-taking behaviours, such as those associated with alcohol/drug abuse.