Background: Behavioral studies suggest that alcohol intoxication impairs the speed and accuracy of word recognition and categorization, but alcohol's effects on the brain during verbal cognitive processing are not adequately understood. Using event-related potentials (ERP) and a word-recognition paradigm, this study investigated the effects of alcohol intoxication on prelexical, semantic, and mnemonic aspects of verbal processing.
Methods: Concurrent measures of ERPs and skin conductance responses were obtained in a word-repetition priming task and permitted a comparison of the effects of alcohol on the central and autonomic physiologic systems. Social drinkers participated in all four cells of the within-subjects balanced placebo design, in which the effects of alcohol and information as to the beverage content (expectancy) were manipulated. The average peak blood alcohol level peaked at 0.045%.
Results: None of the manipulations affected behavioral performance, and expectancy had no effect on any of the measures. In contrast, alcohol ingestion attenuated the temporoparietal N180, suggesting an impairment in prelexical pattern-recognition processes. Alcohol significantly increased the amplitude of N450 and the latency of P580, particularly on trials evoking sympathetic arousal as measured with skin conductance responses.
Conclusions: Although behavioral measures were unaffected, ERPs showed that a moderately low alcohol dose affected verbal processing during both early, prelexical and late, semantic stages. Alcohol significantly increased the difficulty of semantic access and integration, as reflected in larger N450 amplitude and longer P580 latency. This effect was particularly prominent on arousal-related trials, suggesting that alcohol impairs processes that modulate cognitive functioning. The lack of an interaction between the factors of repetition and beverage suggests that a moderately low alcohol dose exerts these effects via the semantic and integration systems rather than via memory processes.