Susan Wells knows only too well when her period is coming.
"On the day I start to ovulate, my reality would change completely. Suddenly I could only remember the bad times. I would look back and think, 'Your whole life has been a mess'. In this state, everything I loved would suddenly repulse me."
Wells, who chose not to use her real name, says: "But the minute I get my period, the clouds would disappear and I would feel invincible."
She likens the monthly pain she has endured for more than 30 years to a searing scalpel being dragged through her uterus.
What Wells has isn't just premenstrual syndrome (PMS). She suffers from premenstrual dysphoric disorder (PMDD), a condition so severe it was classified in 2013 as a mood disorder in psychology's diagnostic bible, the Diagnostic and Statistical Manual . The illness is marked by symptoms such as lethargy, irritability and sudden mood changes, which typically show up in the two weeks between the start of ovulation and when menstruation begins.
If left untreated, the heightened feelings of anxiety and depression brought on by the disorder can be debilitating, according to 2008 research published in the Journal of Psychiatry and Neuroscience.
The condition is thought to affect between 2% and 5% of American women between the ages of 15 and 49, according to a 2012 study published in the American Journal of Psychiatry. There are no statistics on the prevalence of PMDD in South Africa.
The search for a causeWhat causes the condition? Scientists know that women like Wells are sensitive to changes in the levels of the hormones oestrogen and progesterone. These play a role in reproduction and their levels in a woman's body change throughout her menstrual cycle.
But experts are uncertain about why PMDD affects only some people. Now, researchers in the United States have discovered a group of genes that could be at the root of the disorder.
As part of a small study conducted among 67 women, a team from the US National Institute of Mental Health compared blood samples from women who were living with PPMD with samples from those who were not. They found for the first time that genes in white blood cells, which help the body to fight infection, responded to increased levels of oestrogen and progesterone, according to the study published this month in the journal Molecular Biology.
Study co-author and National Institute of Mental Health behavioural endocrinology specialist Peter Schmidt explains that, although the body is home to many different types of cells, all cells share about 70% of the same characteristics.
This means the reaction that white blood cells have to oestrogen and progesterone could be very similar to that of cells in the brain and nervous system that could control PMDD's symptoms.
But he warns that more research is needed to confirm this.
Scientists will also need to test whether the changes they saw in white blood cells' reactions are not attributed to the mood disorder itself. He says studies show that long-term mood disorders can alter the way cells react to hormones.
Schmidt says that understanding PPMD's biological causes will help to dispel myths that the disorder is something women should be able to shake off.
"These findings are an important step in unravelling the condition. Now that we have identified that the cells of women with PMDD process hormones differently because of this cluster of genes, the next step is to further investigate the genes involved and identify possible targets for treatment," he explains.
Diagnosing 'the saboteur' and diagnosing it earlyCape Town-based psychiatrist Bavi Vythilingum says awareness of PMDD has increased, but there are still too many South Africans who do not understand how serious the mood disorder can be.
She says that common anti-depressants such as Prozac can help to treat the persistent mood and anxiety problems associated with PMDD. Hormone-based contraception, including some pills and intrauterine devices, can also be used in combination with the anti-depressants to control symptoms.
Wells says her condition was initially misdiagnosed as Mittelschmerz. Mittelschmerz is derived from the German word for "middle pain" and is a medical term used to describe pelvic pain usually associated with ovulation, according to the US nonprofit organisation, the Mayo Clinic.
Desperate for relief, Wells turned to progesterone treatment at Cape Town's Integrative Medicine Centre, which combines clinical practice with alternative medicine such as homoeopathy.
Progesterone supplements have not been clinically proven to treat PMDD.
Wells says her struggle with the condition had a negative effect on her work life and interpersonal relationships.
A 2003 review of research published in the Journal of Psychoneuroendocrinology estimated that women with PMDD suffer nearly four years of disability between the ages of 15 and 49.
Wells, a nail technician, blames PMDD in part for her decision to close her own nail salon.
She explains: "One very dark month, I decided I hadn't made enough progress with my salon.
"My saboteur [PMDD] decided to give it up and promptly apply for a job on a [cruise] ship instead."
She says earlier diagnosis would have put her in a position to make better life choices.
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