Acute effect of small doses of alcohol on the NSD parameters (normalized slope descriptors) of human EEG.

The acute effect of ethanol upon the NSD (normalized slope descriptors) or Hjorth parameters of EEG were analyzed in 11 students. The maximal blood-alcohol concentration ranged from 1.0--1.7 mg/l. The activity (mean amplitude) increased and the complexity (frequency spread) decreased significantly as a function of time. The same effect was seen in control subjects, but to a lesser degree. The difference between the test and the control group was, however, significant only for the change in complexity. Changes in the mobility parameter (mean frequency) showed most prominently the interindividual differences: in some a transient increase during increasing blood-alcohol concentration, in others a steady falling tendency. It is concluded that changes in the NSD parameters reflect (1) the depressing effect of both alcohol and the test situation, which was more or less evident in most subjects, and (2) the individual degree of and type of CNS reaction to alcohol consumption. From a social and psychologic point of view, the individual reactions are at least as important as the reactions common to all.