The effect of sex steroid hormone levels in healthy adults on nerve conduction velocity, reaction time, cognitive functions and cerebral lateralization

Object: In this study, we aimed to investigate the effects of sex steroid hormone levels on cognitive skills, nerve conduction velocity and right-left hand asymmetry of healthy male and female examined according to menstrual cycle phases. Materials and Methods: Our study was carried out on healthy and voluntary, 30 female and 30 male individuals between the ages of 18-25. In the follicular of each female (3-4th day), in the estrogen (12-15th day) and in the luteal phase (21-22th day) and and once in any time in male, estradiol (E2), progesterone, total serum testosterone, sex hormone binding globulin (SHBG), free testosterone concentrations were measured. Serum estrogen alpha and beta levels were measured by ELISA method. Electromyography (EMG) was measured from the median nerve of the right hand and left hand, and motor nerve conduction velocities were calculated for male and female (in three phases). Cognitive skills tests; Reaction time test (RTms), reaction speed-quality test (DT-DTtime ms) under stress, reasoning test (SPMIQ) and visual perception-attention test (LVT), visual memory test (TAVT) were applied. In addition, BECK depression scale, state anxiety scale (STAI1), trait anxiety scale (STAI2) were applied to the questionnaires which determined the mood. Results: Female (n = 25) had a higher luteal response DT, DTsüre ms, SPMIQ, and TAVT than ovulation and follicular period (p<0.05). The conduction velocities of the dominant hands of right-left-handed male and female were higher than those of the non-dominant hands (p<0.05). The mean nerve conduction velocity in the follicular phase of female was higher than the luteal phase and the latency was shorter. Conclusion: It was concluded that sex steroid hormone levels may have neuromodulatory effects on cerebral asymmetry, brain functions and peripheral nervous system.