Estrogen replacement may help protect women against Alzheimer disease (AD), according to a new study published in the Journal of Alzheimer’s Disease.

Approximately 5.5 million people are affected by AD in the United States alone. An estimated 24 million people are living with dementia worldwide, which is expected to double by 2050, according to the study. Early signs of AD include not being able to form recent memories, before inevitably affecting all intellectual functions. 

This decline will eventually lead to complete dependence for basic functions and premature death. Risk factors include reproductive stage, hormone levels, and age. 

Biological sex influences the effect of amyloid beta on alternations to tau protein characteristics to AD, which means that estradiol may have a role in preventing the disease in women, according to the study. Researchers administered intraventricular injections of nanomolecular concentrations of amyloid beta 42 (AB42) to transgenic mice expressing the wild-type human tau to test this hypothesis. 

Researchers found that AB42 caused the pathological form of tau in ovariectomized female mice, but not in the control group. They also found that estrogen replacement reversed this effect through an antioxidant activity and the decrease of tau phosphorylation. 

"Our study indicates that factors such as age, reproductive stage, hormone levels, and the interplay with other risk factors should be considered in women, in order to identify the best appropriate treatment in prevention of cognitive impairment…Our results suggest that an early postmenopausal estrogen replacement may be protective against AD," co-lead investigator Massimo Tabaton, MD, said in the press release. 

Finding ways to prevent the disease in women is especially important as women have a higher rate of AD than men. One in 6 women over 65 years of age will develop AD, compared with 1 in 11 men.

Reference:
Estrogen replacement may protect against Alzheimer's disease in women (Press release) Amsterdam, Netherlands, September 1, 2020, EurekAlert! Accessed September 3, 2020