Differential trait and state frontal alpha asymmetry in women with premenstrual syndrome

Up to 80% women report physical and emotional symptoms before menstruation and some of them may be diagnosed as Premenstrual Syndrome (PMS). However, the current understanding of the neurobiological mechanisms underlying PMS and the influence of menstrual cycle on emotion is limited. Here we test the hypothesis that frontal alpha asymmetry (a neurophysiological indicator for emotional motivation reactivity) differs between women with and without PMS during resting and emotional state in the early and late phases of a menstrual cycle. Frontal electroencephalographic (EEG) activity was assessed in women with PMS and without PMS. They were assessed during a resting and emotional state in their mid-late luteal phase and late follicular phase. The resting frontal alpha asymmetry was considered as trait and the emotional state consisted of emotive picture stimuli. This study found that women with PMS had a lower frontal alpha asymmetry score during resting state than women without PMS in both phases. During the emotional state, the PMS group had a lower frontal alpha asymmetry score when processing the positive pictures, but a higher frontal alpha asymmetry score when processing the negative pictures, when compared to women without PMS. The menstrual cycle showed little influence on emotional state. The results revealed a neurophysiological dysfunction in the emotional motivation system of women with PMS, which likely contributes to their stronger negative emotional symptoms.