Beyond Normal PMS

Pre menstrual syndrome explained

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Women experience varying levels of pre-menstrual syndrome (PMS), and some even none at all. But severe cases of the syndrome, called premenstrual dysphoric disorder (PMDD) can be almost debilitating.

Fortunately, researchers are making headway into understanding the biology behind PMDD, including identification of a hormone that is largely responsible.

"Ask your doctor about treatment for pre-menstrual symptoms."

Allopregnanolone is a hormone that occurs naturally in the body after ovulation and during pregnancy. A woman's sensitivity to it changes during the course of her menstrual cycle; and sensitivity is also different in women with PMDD, compared to women without any symptoms or complaints of PMS.

Erika Timby a specialist physician at Norrlands University Hospital in Umeå, Sweden, led research that indirectly measured GABA, the principal inhibitory transmitter system in the brain, to study the effects of sensitivity to the hormone.

For women without mood changes just before menstruation, they were less sensitive to allopregnanolone prior to menstruation but more sensitive immediately afterwards.

But women who suffer from PMDD, including pronounced mood shifts, had the opposite sensitivity pattern; they proved more sensitive before menstruation than after.

While researchers were unclear what causes this difference, they theorized that women with sensitivity before menstruation may have less ability to adapt to hormonal variations, leading to premenstrual disorders.

When researchers gave study participants a substance that elevated allopregnanolone to levels normally seen during pregnancy, a fatiguing effect was recorded in the form of slower eye movements and increased feeling of tiredness.

"We have studied few women, but this is one of the first studies to examine the effects of this particular metabolite from the corpus luteus hormone in humans. Greater knowledge of the underlying mechanisms of pronounced PMS can ultimately provide clues for new methods of treatment," Timby said.

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Review Date: 
December 22, 2011
Last Updated:
December 26, 2011