Electrophysiological effects of low dose alcohol on human subjects at high altitude.

Low dose alcohol significantly altered auditory evoked potentials in normal human subjects. Effects of alcohol were studied on the P50 evoked potential wave following click stimulation, which was presented in a conditioning-testing paradigm. The conditioning-testing paradigm uses paired stimuli to demonstrate inhibitory sensory gating, measured as suppression of the amplitude of the second or "test" response following the first or "conditioning" response. Alcohol at blood levels under 0.1 g per dl caused significant decrement in the size of the P50 wave in the initial conditioning response and also decreased the suppression normally seen in the conditioning-testing paradigm. These data suggest that low doses of alcohol affect both the excitatory mechanisms responsible for the formation of the P50 wave in the conditioning response and the inhibitory mechanisms responsible for its suppression in the test response. Nine of the 17 subjects studied using this paradigm were recorded both at Denver, Colorado (5,280 feet above sea level) and on Mt. Evans (14,264 feet above sea level). Despite the commonly held belief that alcohol causes more intoxication at high altitudes there was no significant difference in the effects of alcohol on evoked potentials in these subjects at these two attitudes.