Japanese researchers have revealed women with severe premenstrual syndrome are more likely to have permanently depressed nervous system.
A study led by Tamaki Matsumoto from the International Buddhist University in Osaka investigated whether the activity of the autonomic nervous system, which plays a vital role in equilibrium within the human body, changed during the menstrual cycle.
The researchers examined physical, emotional and behavioural symptoms associated with the menstrual cycles of 62 women.
The findings revealed that the control group with little or no menstrual symptoms did not vary during the month whereas women suffering from PMS reflected a significant decrease in autonomic and parasympathetic nerve activity in the phase preceding menstruation.
Those with the most marked symptoms [known as premenstrual dysphoric disorder (PMDD)] had lower rates of nerve activity than the other groups during the entire menstrual cycle.
Matsumoto said that the findings indicated that premenstrual symptoms could be attributed to altered functioning.
"Our findings indicate that the occurrence of premenstrual symptomatology could be attributable to an altered functioning of the autonomic nervous system in the symptomatic late luteal phase," said Matsumoto.
PMS comprises innumerable non-specific physical, emotional, behavioural, and cognitive symptoms that occur in the days prior to menstruation.
The most prevalent symptoms also include irritability, mood lability, depression, anxiety, impulsivity, feelings of "loss of control," fatigue, decreased concentration, abdominal bloating, fluid retention, breast swelling, and general aches.
The findings are published in the online open access journal BioPsychoSocial Medicine.