© Judywie / photocase.com

Munich (netdoktor.de) – if women just before menstruation are irritated and anxious, has this a tangible reason that has nothing to do with hormones. As US researchers have now shown, the docking points for the nerve Messenger substance GABA vary at the end of the menstrual cycle in the brain. As a result, women can worse deal with stress and anxiety. Andrea Rapkin and her colleagues from the University of California to present their research in the journal “Biological Psychiatry” (doi:10.1016/j.biopsych.2010.09.029).

Shortly before the period, irritability, anxiety, depression, breast tenderness – have to many women with psychological and physical complaints. In lighter cases, physicians speak syndrome (PMS), in severe cases of the Prämenstruellen of the Prämenstruellen dysphoric disorder – short PMDS or PMDD (for English “premenstrual dysphoric disorder”).

Look in the brain

To go the causes of complaints to the bottom, the team to Rapkin took the brain of twelve women with PMDD and twelve healthy subjects under the microscope. The activity of the individual areas of the brain in the two phases of the menstrual cycle was measured by PET – the follicular phase (first day of menstruation to ovulation) and the Lutealphase (ovulation until next menstrual period).

Also, the researchers analyzed blood samples of to measure the estrogen and progesterone levels women and identified changes in the mood of women on the basis of questionnaires.

Modified receptors

The results: The hormonal levels in the blood differed between the PMDD group and the control group–to any phase of the menstrual cycle. For this, there were clear differences in brain activity: women with PMDD – but not the healthy subjects – showed in the second half of the cycle an increasing brain activity in the area of the cerebellum. At the same time, the mood of women deteriorated, they were for example nervous and timid.

According to Rapkins research of rising against the end of the cycle, progesterone levels the docking points for GABA changed in the cerebellum so that neurotransmitters cannot bind worse. This, he can no longer give its relaxing and anti-anxiety effect – nervousness and panic feelings are on the increase.

How many women of PMS and PMDD are affected, can be difficult to estimate. The information on the frequency of PMS vary between 20 and 50 per cent of child-bearing women. At about five percent of doctors due to the severity of the complaints diagnose a PMDD. (mf)