Extreme Pre-Menstrual Syndrome? Scientist Say It Might Be Caused By a Parasite Carried by Cats

Extreme PMS? Scientists say the symptoms may be caused by a parasite carried by your CAT

• Researchers have found parasite may be linked to severe forms of PMS
• Parasite has previously been linked with anxiety, aggression and schizophrenia
• One in 12 women suffers from a severe form of premenstrual syndrome

For some women, that time of the month can be so bad it triggers a complete emotional meltdown.

But those who suffer severe forms of premenstrual syndrome may be suffering from more than raging hormones – their symptoms could be caused by a parasite carried by cats, research suggests.

Scientists found women with extreme symptoms such as depression and anger are more likely than others to have the parasite in their bloodstream.



Researchers have found a parasite carried by cats may be linked with extreme PMS (file photo)

Called toxoplasma gondii, the organism can be caught by handling cat litter and has previously been linked with anxiety, aggression and schizophrenia in humans.

Now, for the first time, researchers have found it may be linked with extreme PMS too.

Millions of women of reproductive age put up with monthly mood swings, bloating and tummy pain as their period approaches.


But up to one in 12 suffers a severe form, called premenstrual dysphoric disorder (PMDD). It can cause persistent depression, extreme anger, low self-esteem and even suicidal thoughts. Until now it was thought that severe cases were probably due to a complex interaction between hormones and genetic susceptibility.

But new findings suggest cats could also be making some women ill each month. Toxoplasma gondii is a tiny single-cell parasite commonly found in cats’ droppings, as well as in raw meat.

Researchers from the Juarez University of Durango State, Mexico, studied 151 women with PMDD and took blood samples to look for the signs of the toxoplasma parasite. Ten of the women were found to be carrying the organism.



One in 12 women suffers from a severe form of PMS. It can cause persistent depression, extreme anger and low self-esteem (file photo)

When scientists compared symptoms, they found the infected women were nine times more likely to report feeling ‘out of control’ or ‘overwhelmed’ in the run up to their period than those who were parasite-free. Other symptoms – such as difficulty concentrating – were no worse.

Researchers admitted the study was small and that more work was needed to verify the findings. But they wrote in the Journal of Clinical Medical Research: ‘The results of this first study of its kind suggest toxoplasma gondii infection might be linked to some symptoms of premenstrual dysphoric disorder.

‘Infection has been linked to psychiatric disorders and changes in behaviour.’

According to the NHS Choices website, up to a third of us will be infected with the cat-related parasite at some point but not even notice any symptoms.

There are estimated to be around ten million cats in the UK. They are infectious for a week or two, then become resistant to the parasite.

For years, pregnant women have been advised to avoid emptying cat litter trays, as accidentally ingesting the parasite via unwashed hands in early pregnancy can cause miscarriage or stillbirth.

In adults, it can also lead to blindness by causing scarring at the back of the eye.

In recent years, studies have linked the parasite with psychiatric illness. Once inside the body, the organism can travel to the brain, where it is thought to interfere with mood-altering chemicals.

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