Yeah, the same excuse, she's got a head ache... which will disappear anyway after she has sex... but not with you ...Anyhow, she is three times more likely than you to have a migraine (but you're xxx times more likely to desire sex...). About 18-25 % of the women experience severe headaches, often accompanied by nausea, sensitivity to light and sound, and aura, being one of the most common disabling conditions affecting women around the globe.

But why are women much more exposed to this? An UCLA team believes that women could have a faster trigger than men for turning on the brain waves causing the migraines. In this case, a new target for migraine treatment should be taken into consideration.

The UCLA team employed a mouse model to find a big difference between males and females concerning the cortical spreading depression (CSD), which seems to be the main factor provoking migraines. Memantine, a drug that blocks CSD waves, has been found to be effective against migraines.

"Migraines were once thought to be caused primarily by constriction and dilation of blood vessels. Now, thanks to various neuroimaging techniques, it has been shown that migraines may begin as a problem of brain excitability. Patients with migraines show cortical spreading depression, which is characterized by dramatic waves of activity that spread across the surface of the brain. CSD may in turn trigger not only the pain of migraine but the visual symptoms, nausea, dizziness and difficulty concentrating so common in migraine patients." said co-author Dr. Andrew Charles, director of the Headache Research and Treatment Program in the UCLA Department of Neurology.

Imaging techniques enabled the researchers to visualize the start and spread of CSD in anesthetized male and female mice. Female mice have a much lower threshold for CSD compared to males, thus they got migraines much easier than the males do. "The results were very clear. The strength of the stimulus required to trigger CSD in males was up to two or three times higher than that required to trigger the response in females. A variety of factors may reduce the CSD threshold in both sexes, making them more susceptible to migraines - these include genes, hormones and environmental triggers such as stress, diet, changes in sleep patterns and a host of others." said Charles.

"While it is known that migraines in females fluctuate with the menstrual cycle and are more frequent during the menstrual period, the study results appear to be independent of a specific phase of the cycle. We didn't monitor the estrous cycle in the female mice, so it's likely we sampled from different estrous phases in different animals. Yet we still found a consistent difference in the CSD threshold between males and females. Our results suggest that the female brain has an intrinsic excitability that predisposes them to migraine that may not be simply linked to a specific phase of the menstrual cycle.", he added.

"These results are exciting, because they may represent a model for understanding the mechanisms underlying the increased prevalence of migraine in women. In addition, they add to growing evidence that CSD is a key target for the development of new migraine treatments."

The same team showed that memantine (commercialized as Namenda) - currently employed against Alzheimer's disease - hampers CSD and seems to be very effective in the case of some chronic migraine.

From 54 subjects who received memantine for at least two months, about 36 reported a significant decrease in the estimated headache frequency. Other medications didn't work in their case.