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There is no clear link between women’s negative moods and the pre-menstrual phase of their cycles, according to a review of research led by University of Toronto experts.

The team analyzed 41 research studies that tracked women’s daily moods through their menstrual cycles. Their findings — which showed no clear evidence that pre-menstrual syndrome (PMS) exists — are published online now in the journal Gender Medicine and are drawing international attention in the news world and blogosphere.

“There is so much cultural baggage around women’s menstrual cycles, and entire industries built around the idea that women are moody, irrational — even unstable — in the phase leading up to menstruation,” says Dr. Gillian Einstein, director of �鶹��Ƶ’s collaborative program in Women’s Health and one of several �鶹��Ƶ experts who reviewed the literature. “Our review — which shows no clear evidence that PMS exists — will be surprising to many people, including health professionals.”

Of the 41 papers the panel examined, only six (or 13.5 per cent) showed any association between negative moods and the pre-menstrual phase, says Einstein, an associate professor in the Department of Psychology and the Dalla Lana School of Public Health. Further, the team found that some of those studies may even have been biased because study participants were not “blinded” to the purpose of the study.

“Before women even get their first period, they have heard about PMS. The notion is so ingrained in our culture that some of these studies are actually biased because women know the study is about PMS,” says Einstein, also a senior scientist with Women’s College Hospital and a scientific associate with Sunnybrook Health Sciences Centre.

The review did not address the existence of premenstrual dysphoric disorder (PMDD), a clinical mood disorder linked with the menstrual cycle that is characterized by severe physical and behavioural symptoms in the latter half of the menstrual cycle. It also did not discount the existence of physical symptoms such as bloating and cramping related to the pre-menstrual phase.

Einstein says the research demonstrates the need to examine other factors which may affect women’s moods so that the real challenges can be treated.

“There are so many things going on in women’s lives that can have a distinct impact on their moods — stress, lack of social support, economic hardship, physical ailments,” she says. “Looking at these factors is key to the concept of evidence-based medicine.

"Once we understand the real problems, we can deliver solutions.”