Effects of acute alcohol consumption on complexity and functional connectivity of EEGs in healthy subjects

Abstract

Although alcohol ingestion, particularly in excess, is well known to result in physiological, cognitive and behavioral dysfunctions in animals, the effect of alcohol on brain dynamics is poorly understood. The aim of this study was to examine the effect of alcohol and cognition on cortical complexity and functional connectivity in healthy subjects. EEGs were recorded before alcohol consumption as a baseline and 1 hour after acute alcohol consumption (alcohol dose: 1.5g/kg) from 14 healthy males in a resting condition and during a mental arithmetic task. The approximate entropy (ApEn), a statistical measure of regularity, was used to estimate the complexity of EEG recordings and partial directed coherence (PDC) was used to measure the directional information inflow between cortical regions. We found that, in subjects after alcohol administration, the EEG exhibited significantly decreased ApEn values in the parietal, temporal, and occipital regions, compared with normal states. More significantly, The PDC analysis revealed that the subjects after alcohol consumption exhibited an increase in PDC values (i.e. functional connectivity) in delta, theta, and alpha bands in the frontal regions and a decrease in right hemisphere dominant synchronizations. These results suggest that alcohol consumption produce a decrease in complexity and abnormal rearrangement in functional connectivity, possibly arising from the cortical impairment due to alcohol consumption. Our findings support the idea that the ApEn and PDC can be useful assessment tools for evaluating the effects of alcohol on the brain dynamics.