New research suggests that older women who have both high estrogen levels and diabetes have a significantly higher risk of dementia, compared with older women who do not have these combined conditions. This is according to a study published online in Neurology.
According to the Alzheimer's Association, more than 5 million Americans are living with Alzheimer's disease - the most common form of dementia.
Diabetes is a risk factor for dementia. Last year, Medical News Today even reported on a study detailing a new dementia risk scoring system that can predict whether older individuals with type 2 diabetes are likely to develop the condition.
But in this study, Dr. Pierre-Yves Scarabin, of the French National Institute of Health and Medical Research (INSERM) in Villejuif, France, and investigators found that diabetes combined with high estrogen levels may increase the risk even further.
To reach their findings, the research team measured blood estrogen levels of 543 women aged 65 or over who were free of dementia, alongside 132 who had the disorder.
All women were assessed for risk factors for dementia, including diabetes, high blood pressure and abnormal blood clotting, among other heart health risk factors.
Dementia risk 14 times higher with diabetes and high estrogen levels
The investigators found that women who had high estrogen levels were more than twice as likely to develop dementia, compared with women who had low estrogen levels.
However, the researchers found that women who had both high estrogen levels and diabetes were 14 times more likely to develop dementia, compared with women without diabetes who had low estrogen levels.
The research team also found that women with both dementia and diabetes had estrogen levels 70% higher than women who only had diabetes.
Dementia risk was not increased with any other heart health risk factors.
Previous research has suggested that estrogen-based therapy may have protective effects on the brain. Therefore, Dr. Scarabin says the research team was surprised with the study results, adding:
"However, more and more evidence suggests an association between high estradiol levels and dementia in women who have undergone menopause.
Considering the expected increase in the number of elderly people with diabetes and dementia, more research on this topic should be urgently conducted."
This is not the only research to analyze the effects of estrogen on the brain.
In 2012, Medical News Today reported on a study from Johns Hopkins University in Baltimore, MD, suggesting that hormone therapy may affect women's risk of Alzheimer's disease, but that the risk depends on the timing of the therapy.
They found that women who undergo hormone therapy before menopause may have a lower risk of Alzheimer's disease, but starting any later may lead to an increased risk.