Ethanol and menstrual cycle interactions in the visual evoked response.

Right and left hemisphere visual evoked responses from central locations were collected from 10 normal right-handed women in the follicular and luteal phases of their menstrual cycle. Subjects were tested sober and under 3 doses of ethanol. Amplitude and latency characteristics of the N120 and P180 components for each hemisphere were determined. Asymmetry between hemispheres for the various measurements was then calculated. The follicular phase was associated with a significant P180 latency asymmetry under baseline or placebo conditions. Virtually no asymmetry for P180 latency was present in the luteal phase. Ethanol eliminated the follicular P180 latency asymmetry and reduced the amplitude of both N120 and P180 in a dose-related fashion. The latency of the N120 component was prolonged by ethanol in a similar fashion. Interactions between menstrual cycle and ethanol occurred for both amplitude and latency of P180, but only for the response from the left hemisphere. These occurred at low or moderate doses of ethanol and illustrate the need to consider both the biphasic effects of low doses of ethanol and the possibility of lateralization of these effects to one cerebral hemisphere.