Scientific clue behind PMS
PMS can cause irritability and abdominal bloating
Thursday, 20, Dec 2007 09:00
Women who suffer from premenstrual syndrome (PMS) may have a permanently depressed nervous system, scientists believe.
Although PMS affects most women to some extent, the researchers behind the latest discovery say until now science has not offered a biological explanation as to why it happens.
They claim in the journal BioPsychoSocial Medicine to have found that PMS is linked to decreased nerve activity each month and those with extreme symptoms could have this permanently.
PMS consists of non-specific physical, emotional, behavioural and cognitive symptoms in the days prior to menstruation and include irritability, anxiety, abdominal bloating and breast swelling.
The team of Japanese researchers studied whether these are due to monthly changes in activity in the automatic nervous system, which helps equilibrium within the body.
They measured heart rate variability and hormone levels and used questionnaires to evaluate physical, emotional and behavioural symptoms accompanying 62 women's menstrual cycles.
These parameters did not vary during the month in women with little or no menstrual symptoms.
But women suffering from PMS had a significant decrease in results reflecting autonomic and parasympathetic nerve activity during the phase that precedes menstruation (late luteal phase).
Females 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.
"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 lead researcher Tamaki Matsumoto.