The effect of alcohol on cortical complexity in healthy subjects measured by approximate entropy

The aim of this study was to examine the effect of alcohol on cortical information processing estimated by EEG using Approximate Entropy (ApEn). The EEG was recorded before alcohol consumption as a baseline and 1 hour after alcohol consumption (alcohol dose: 1.5g/kg) from fourteen healthy males (mean age: 24.14 ± 2.96) during resting state and mental arithmetic task. ApEn was estimated for the EEG recordings as a measure of complexity, and the surrogate data method was used to test the validity of the nonlinearity in the EEG. In a resting condition, EEGs one hour after alcohol administration exhibited significantly lower ApEn in the left frontal (F3), right central and right parietal (C4 and P4), temporal (T4, T5, and T6), and occipital lobes (O1 and O2). More interestingly, during mental arithmetic tasks, alcohol significantly reduced the ApEn values in the left frontal (Fp1 and F3), left central (C3), right temporal (T6), and occipital (O1 and O2) regions. These results suggest that alcohol intake gives rise to reduced cortical complexity, which is possibly associated with cortical and behavioral impairments during alcohol consumption. These findings also suggest that the ApEn is useful in evaluating the effect of alcohol on the brain electrical activity.