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Estrogen Replacement May Protect Against Alzheimer’s Disease in Women

Biological sex influences the effect of amyloid beta on alterations to tau protein characteristic to Alzheimer's disease, suggesting a role for estradiol in preventing the disease in women, report scientists in JAD

September 1, 2020
Amsterdam, NL – Alzheimer's disease (AD) is the most common neurodegenerative disease and the leading cause of dementia. It affects more women than men. A new study published in the Journal of Alzheimer’s Disease indicates that factors such as age, reproductive stage, hormone levels, and the interplay with other risk factors should be considered in women and proposes a role for early menopausal estrogen replacement to protect against the development of AD.

“The risk of developing AD as well as its progression and severity are known to be very different in men and women,” explained co-lead investigator Elena Tamagno, PhD, Department of Neuroscience and Neuroscience Institute of Cavalieri Ottolenghi Foundation (NICO), University of Torino, Torino, Italy. “Recent epidemiological studies showed that two thirds of AD patients are women, and this fact cannot be attributed only to their higher life expectancy. The loss of estradiol might be one of the factors leading to declining cognitive function in women.”

Hallmarks of AD are the accumulation of amyloid beta peptides in amyloid plaques, and the aggregation of modified tau protein to form neurofibrillary tangles. Tau proteins are abundant in nerve cells and perform the function of stabilizing microtubules, and are pathologically altered in AD. To examine the hypothesis that biological sex influences the effect of amyloid beta 42 (AB42) peptides on these changes to tau protein, investigators gave intraventricular injections of nanomolecular concentrations of AB42 to transgenic mice expressing the wild-type human tau (hTau). In a previous study the investigators had noted that female mice did not show the alterations of tau protein characteristic of AD. In the current study they demonstrated that AB42 caused the pathological form of tau in ovariectomized female mice, but not in control females, and that estrogen replacement reversed this effect through an antioxidant activity and a 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,” commented co-lead investigator Massimo Tabaton, MD, Unit of Geriatric Medicine, Department of Internal Medicine and Medical Specialties, University of Genova, Genova, Italy. “Our results suggest that an early postmenopausal estrogen replacement may be protective against AD.”

“Linking estrogen deficiency to the tau changes of AD provides the missing mechanistic link to the greater risk of AD in women and significantly suggests therapeutic avenues to reduce AD,” added George Perry, PhD, Editor-in-Chief of the Journal of Alzheimer’s Disease and Semmes Foundation Distinguished University Chair in Neurobiology at The University of Texas at San Antonio.

AD is a major social and health problem. In the United States, approximately 5.5 million people are affected, and the number is growing as a result of the increase in life expectancy. The prevalence of dementia worldwide is estimated at 24 million people, which is expected to double by 2050. AD is characterized by progressive cognitive decline usually beginning with impairment in the ability to form recent memories, but inevitably affecting all intellectual functions and leading to complete dependence for basic functions of daily life and premature death. Women are more likely to develop the disease, independent of their longer life expectancy: one in six women over 65 develops AD, compared with one in 11 men.

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NOTES FOR EDITORS
Full study: “Estrogens Inhibit Amyloid-Beta-Mediated Paired Helical Filament-Like Conformation of Tau Through Antioxidant Activity and miRNA 218 Regulation in hTau Mice” by Michela Guglielmotto, Giusi Manassero, Valeria Vasciaveo, Marika Venezia, Massimo Tabaton, and Elena Tamagno (https://doi.org/10.3233/JAD-200707). The article appears online in advance of the Journal of Alzheimer’s Disease, Volume 77, Issue 3 (September 2020) published by IOS Press. The study is available at: content.iospress.com/articles/journal-of-alzheimers-disease/jad200707.

Contact
To request the full text of the article or further information please contact Diana Murray, IOS Press (+1 718-640-5678 or d.murray@iospress.com). To reach the authors for comment please contact Massimo Tabaton (+393470646063 or mtabaton@neurologia.unige.it). For questions about the Journal of Alzheimer’s Disease, please contact George Perry (+1 210-458-8660 or george.perry@utsa.edu).

About the Journal of Alzheimer’s Disease
Now in its 23rd year of publication, the Journal of Alzheimer’s Disease (JAD) is an international multidisciplinary journal to facilitate progress in understanding the etiology, pathogenesis, epidemiology, genetics, behavior, treatment, and psychology of Alzheimer’s disease. The journal publishes research reports, reviews, short communications, book reviews, and letters-to-the-editor. Groundbreaking research that has appeared in the journal includes novel therapeutic targets, mechanisms of disease, and clinical trial outcomes.JAD has a 2019 Journal Impact Factor of 3.909 according to Journal Citation Reports (Clarivate, 2020). It is published by IOS Press. j-alz.com

About IOS Press
IOS Press is headquartered in Amsterdam with satellite offices in the USA, Germany, India and China and serves the information needs of scientific and medical communities worldwide. IOS Press now publishes more than 80 international peer-reviewed journals and about 75 book titles each year on subjects ranging from computer science, artificial intelligence, and engineering to medicine, neuroscience, and cancer research. iospress.com