Progesterone mediates the late positive potentials evoked by affective pictures in high neuroticism females.

BACKGROUND Neuroticism, which is a personality trait characterized by the tendency to experience negative affect, is associated with premenstrual negative emotion changes. The present ERP study intended to investigate how neuroticism and the menstrual cycle influence the evaluation of emotion as a function of the tested levels of ovarian hormones. METHOD Forty-two healthy females with regular menstrual cycles were grouped by neuroticism (N): 16 were included in the high-N group, and 26 were included in the low-N group. Each female performed an emotion evaluation task in the early follicular phase, late follicular phase and luteal phase while the ERPs, hormone samples and Pleasure-Arousal-Dominance (PAD) mood ratings were measured. RESULTS The PAD and behavioral data did not differ between the two groups during the three phases. However, the mean amplitude of the Late Positive Potentials (LPP, 300-1000ms post-stimulus) of ERPs was significantly larger in the high-N group than that in the low-N group. Moreover, the interaction between the group and phase was significant 2000-4000ms post-stimulus: for the high-N group, the LPP of the luteal phase was the largest, followed by the late follicular phase and the early follicular phase; whereas the LPP of the luteal phase was the largest, followed by the early follicular phase and the late follicular phase for the low-N group. More importantly, the LPP (300-4000ms post-stimulus) evoked by positive pictures from the central or parietal area was significantly negatively correlated with the progesterone level in the early follicular phase. CONCLUSIONS The present study provides electrophysiological evidence showing that both the menstrual cycle and neuroticism modulate the LPP evoked by emotional pictures. Furthermore, the negative correlation between progesterone and the amplitude of the LPP suggests that the effect of the menstrual cycle on the LPP may be primarily a function of progesterone. These findings suggest that the LPP evoked by emotional pictures for high and low neuroticism females change throughout the menstrual cycle and that this change is in part mediated by progesterone.