Alcohol effects on movement-related potentials: A measure of impulsivity?

Objective: To assess the effects of acute alcohol intoxication on lateralized readiness potential (LRP), a central measure of movement-related brain activity, and the potential association of such effects with personality measures. Method: Male volunteers (N = 12) alternated responding hands during a "go/no go" verbal recognition task across all four sessions of the balanced placebo design in which beverage content (either juice only or a vodka and juice mixture that raised the average blood alcohol concentration to 0.045%) was crossed with instructions as to beverage content. Results: Whereas the instructions had no effect on behavioral (response accuracy and reaction time) and physiological (LRP) measures, alcohol decreased reaction times adjusted for psychometer speed. As expected, large LRPs were recorded on "go" trials and were not affected by the beverage. However, the "no go" words that did not require and did not evoke motor responses, also evoked significant LRPs under alcohol but not placebo. Since only trials with correct responses and correct abstentions from responses were included in the averages, the motor preparation was nor completed and was terminated before the motor response on "no go" trials. Similarly, there was a decrease in spectral power of the movement-related mu-rhythm on "no go" trials under alcohol. Conclusions: Alcohol may result in disinhibition such that the "response execution" process is activated based on very preliminary stimulus evaluation. This alcohol-induced brain activity signaling premature motor preparation exhibited correlation trends with personality traits related to impulsivity, hyperactivity and antisocial tendencies, thus concurring with other evidence that indicates commonalities between alcoholism and impulsivity, disinhibition and antisocial behaviors. The LRP on "no go" trials could potentially be used as a psychological index of the impulsiveness induced by alcohol intoxication.