  Many sexually mature women experience premenstrual syndrome (PMS) or
premenstrual dysphoric mood disorder (PMDD). Current approaches for managing
PMS and PMDD rely on daily mental condition recording, which many discontinue
due to its impracticality. Hence, there's a critical need for a simple,
objective method to monitor mental symptoms. One of the principal symptoms of
PMDD is a dysfunction in emotional regulation, which has been demonstrated
through brain-function imaging measurements to involve hyperactivity in the
amygdala and a decrease in functionality in the prefrontal cortex (PFC).
However, most research has been focused on PMDD, leaving a gap in understanding
of PMS. Near-infrared spectroscopy (NIRS) measures brain activity by
spectroscopically determining the amount of hemoglobin in the blood vessels.
This study aimed to characterize the emotional regulation function in PMS. We
measured brain activity in the PFC region using NIRS when participants were
presented with emotion-inducing pictures. Furthermore, moods highly associated
with emotions were assessed through questionnaires. Forty-six participants were
categorized into non-PMS, PMS, and PMDD groups based on the gynecologist's
diagnosis. POMS2 scores revealed higher negative mood and lower positive mood
in the follicular phase for the PMS group, while the PMDD group exhibited
heightened negative mood during the luteal phase. NIRS results showed reduced
emotional expression in the PMS group during both phases, while no significant
differences were observed in the PMDD group compared to non-PMS. It was found
that there are differences in the distribution of mood during the luteal and
follicular phase and in cerebral blood flow responses to emotional stimuli
between PMS and PMDD. These findings suggest the potential for providing
individuals with awareness of PMS or PMDD through scores on the POMS2 and NIRS
measurements.
