Scientists have raised the prospect of a cure for pre-menstrual tension or syndrome after identifying key genes thought to be responsible for the condition.
Up to 5 per cent of women are believed to suffer from the most severe form of PMS.
The condition is defined as a mood disorder with a woman showing a disabling irritability, sadness and anxiety in the days leading up to her period.For years debate has raged over whether sufferers are simply unable to control their emotions rather than suffering a physical ailment.
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But now researchers say the condition is a heightened sensitivity that makes women overreact to their two key sex hormones oestrogen and progesterone.
Their findings highlight genetic differences in severe PMS sufferers from those who are unaffected by the condition.The effect is that a woman with PMS genes' suffers mood problems, with her brain function disrupted as some genes become excessively active in response to the hormones, while others become much less active.
Women without the gene variations do not show the same erratic response. It is thought to be the first time a biological cause for the disorder has been found, although it had previously been suspected that genes may play a role.
Researchers estimate that around 56 per cent of women whose mothers suffered severe PMT will also suffer the disorder. Peter Schmidt from the National Institutes of Health, a leading medical research centre based in the US, said: For the first time, we have cellular evidence of abnormal signalling in cells derived from women with severe PMS, and a plausible biological cause for their abnormal behavioral sensitivity to oestrogen and progesterone.
Learning more about the role of this gene complex holds hope for improved treatment of such prevalent reproductive endocrine-related mood disorders.'
Commenting on the research published in Molecular Psychiatry, Dr Schmidt added: This is a big moment for women's health, because it establishes that women with severe PMS have an intrinsic difference in their molecular apparatus for response to sex hormones not just emotional behaviours they should be able to voluntarily control.'
Around 70 women were studied by the researchers, half of which were suffering from extreme PMS.
The sufferers were selected by questions that assessed how much their lives were impaired in the days prior to their period. In white blood cells taken from the women and a control group unaffected by the condition, they found that genes described as ESC/E(Z) were over-expressed' in sufferers.
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The result is that the cells become disordered' in response to sex hormones, because these white blood cells exhibit many of the traits in brain cells, the authors suggest this could be a genetic explanation for the impact of PMS.
They added that factors such as stress can influence the severity of the condition.