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.
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The investigators also looked at risk factors for dementia, including
blood pressure and other heart
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,"
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
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",
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
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