Electrophysiological and psychological changes induced by steroid hormones in men and women.
The effects of hormonal changes during the menstrual cycle and of oral contraceptives on the EEG, heart-rate and a number of performance tasks were investigated in 16 female subjects (Ss). Powerspectral analysis in the EEG revealed significantly increased alpha-frequencies and heart-rates during the luteal phase of the menstrual cycle whereas the mean theta-frequency and power decreased. A number of psychological test variables, such as reaction time to a tone, to a flickering light and to a colour-tone sequence and the time to solve simple arithmetic problems was shorter at the periovulatory time. Another minimum was reached during the perimenstrual phase. The flicker-fusion-frequency was higher during these two periods. No such effects could be observed when the same Ss were treated with oral contraceptives. It is concluded that the phenomena observed during the luteal phase of the cycle may be the expression of a slight general arousal effect, possibly medicated by progesterone via the noradrenergic system. In a subsequent double blind study 30 male Ss were treated with an gestagenic compound (D-Norgestrel, 2.5 mg/die), an estrogenic compound (estradiolvalerate, 5 mg/die), an androgenic substance (Mesterolone, 100 mg/die) or with placebo. Only treatment with the progestational compound revealed significant changes in the EEG and the performance tests. These changes were qualitatively similar to those observed during the luteal phase of the female Ss. Under both conditions, i.e. the luteal phase and D-Norgestrel treatment, the body-temperature was significantly increased. Hence, the question whether gestagens exert their effects directly on CNS structures which modulate EEG appearance and behavior or indirectly via increased body-temperature cannot be answered convincingly.