The effects of consumption of low doses of ethanol (0.75 ml/kg) on spectral components of the EEG were investigated in 24 21–25-year-old males. A comparison of mean spectral power in 4 frequency bands (4–7 Hz, 7.5–9 Hz, 9–12 Hz, and 12–20 Hz) at 90 min post consumption revealed that ethanol, as opposed to placebo, significantly increased power in the two slower frequency bands, in both posterior and anterior leads. A reduction in the frequency at which power values peaked in the theta (4–7 Hz), fast alpha (9–12 Hz), and beta (12–20 Hz) frequency ranges was also seen following ethanol consumption. The ethanol induced lowering of peak power in the fast alpha range was observed in all 4 leads (F4-C4, P4-O2, F3-C3, and P3-O1), whereas the frequency changes in the theta and beta frequencies were only significant in a frontal lead. Ethanol was also noted to produce a decrease in the stability of the EEG in the fast alpha band as quantified by the coefficient of variation of power. Subjective response to ethanol was observed to vary depending on the subjects' pre-drug EEG pattern. Men with high amounts of fast alpha activity at baseline, in lead P4-O2, reported feeling less ‘high’ and less overall feelings of intoxication after ethanol than the men with lower amounts of pre-drug fast alpha waves. In addition, subjects were sorted into ‘low’ and ‘moderate’ drinkers depending on their quantify and frequency of drinking over the previous 6 month period. ‘Moderate’ drinkers were found to have more energy in the beta frequencies at baseline and 90 min post drug than ‘low’ drinkers. These results suggest that low doses of ethanol can produce fairly predictable changes in the frequency and content of theta and slow frequency alpha waves, whereas responses in the higher frequency ranges differ in relationship to such variables as drinking history and resting EEG patterns.
