30 January 2014

High oestrogen in older women ups dementia risk

New research suggests that older women with high levels of the hormone oestrogen may be at a greater risk for dementia, especially if they also have diabetes.

Older women with high levels of the hormone oestrogen may be at a greater risk for dementia, especially if they also have diabetes, new research suggests.

Using data from a large study that included more than 5 600 postmenopausal women aged 65 or older, French researchers measured oestrogen levels in those without dementia who were not on hormone replacement therapy, medication that boosts oestrogen levels.

Four years later, the scientists followed up by comparing the baseline oestrogen levels they'd taken of 543 women from the study who did not have dementia with 132 women who had been diagnosed with dementia.

Read: Why hormones may be better than soy for hot flushes

Risk factors

The investigators also looked at risk factors for dementia, including diabetes, high blood pressure and other heart health issues.

The researchers said the risk of dementia more than doubled for women who had high oestrogen levels, even after accounting for other known risk factors for the memory-robbing disease. The findings are published in the online edition of Neurology.

The risk increased even more in women with high oestrogen levels and diabetes combined. Oestrogen levels were about 70% higher in women with diabetes who also had dementia compared to those without dementia.

"Women with high E2 [oestrogen] levels and diabetes may represent a group at very high risk of dementia," the study authors concluded.

The results were a surprise, said lead investigator Dr Pierre-Yves Scarabin, director of research at the French National Institute of Health and Medical Research (INSERM) in Villejuif, France. "We found an association between high levels of endogenous oestrogen and the risk of dementia in older women not using hormone therapy," he said.

Higher oestrogen levels and body fat

Endogenous oestrogen is a hormone that the body makes naturally, explained Dr David Carr, a professor of medicine and neurology in the division of geriatrics and nutritional science at Washington University School of Medicine in St Louis. Oestrogen levels go down after menopause, yet some women may have higher levels due to the amount of body fat they have, he noted.

"While it was long believed that oestrogens – either endogenous or therapeutic – were good for women's health, especially for the heart and brain, our study together with other current data challenge this dogma," said Scarabin.

While the study found an association between oestrogen levels and dementia risk, it did not prove a cause-and-effect link.

Dr Sam Gandy, director of the Centre for Cognitive Health at the Mount Sinai Hospital in New York City, said, "It's a very interesting study. The most surprising thing is the fact that oestrogen is so potent as a risk factor for dementia."

The critical window

Gandy said there has been a fair amount of research conducted over the past five years showing that higher oestrogen levels prior to the age of dementia risk – before age 65 – reduces the risk for dementia. "But once they enter the age of risk for Alzheimer's, higher oestrogen seems to make things worse and that seems to be borne out by this study," said Gandy, also the associate director of the Mount Sinai Alzheimer's Disease Research Centre.

It's referred to as the "critical window of oestrogen therapy", said Carr.

But this study suggests that once that "critical window" closes, a woman with elevated hormone levels may be at a higher risk for dementia, said Carr. "And it also suggests that the combination of diabetes and high oestrogen has an even greater effect on dementia risk."

Does the research suggest that older women who take hormone replacement therapy stop – especially those with diabetes?

Scarabin said the study is not a hormone study – the women involved in the research were not taking oestrogen – and the results do not suggest women who take oestrogen go off of their medication.

Gandy said, "Before we make recommendations, we need to do clinical trials. We'd need to see if women on oestrogen at age 'X' versus a same-age placebo group who did not get oestrogen had the same effect."

Scarabin added that women with both diabetes and elevated oestrogen levels would be a good "target for future prevention studies".

Read more:

Men influenced by oestrogen too

Oestrogen after menopause improves memory

Oestrogen drug tied to heart problems





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