The way Alzheimer's disease is manifested in the brain is significantly influenced by female sex hormones, according to a recent study conducted by researchers from the University of Western Ontario.
The study's findings were published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
Globally, around 32 million individuals have Alzheimer's disease, with approximately two-thirds of those affected being women.
Even though some researchers have put forward theories to explain why women are more susceptible to Alzheimer's disease than men, the precise biological mechanisms underlying this gender disparity are not yet fully understood.
The risk of Alzheimer's disease in women is believed to be higher than in men for a few reasons.
One of these reasons is that women tend to live longer than men, approximately 5.2 years more in high-income countries and 3.8 years more in low-income countries.
Genetics may also play a role, as a gene on the X chromosome was identified in a study published in October 2022 that enhances the accumulation of tau protein in the brain. Since females have two X chromosomes, they may have higher levels of tau protein, which is one of the leading causes of Alzheimer's disease.
Additionally, researchers suggest that women may be more susceptible to Alzheimer's disease due to different hormone levels. A study in mice published in March 2022 found that follicle-stimulating hormone levels, which increase during perimenopause, are linked to Alzheimer's risk.
Furthermore, a 2023 study found that menopausal women who experience frequent hot flashes during sleep are at a higher risk for Alzheimer's disease.
A scientist and a professor recently studied Alzheimer's disease. They wanted to understand how female hormones might affect the disease. In Alzheimer's, the brain undergoes chemical changes, and one crucial chemical is acetylcholine. Women's hormones, such as estradiol, influence this chemical.
When they looked at mice, they saw that male and female mice reacted differently to these hormones. But when they looked at people with Alzheimer's, both men and women seemed similar. So, they wondered why there was a difference between mice and humans.
They think it might be because of the hormones and also because mice used in research are much younger than the people who get Alzheimer's.
In this study, researchers focused on the female hormone estradiol, which is essential for a woman's reproductive system and plays a role in the menstrual cycle.
They looked at brain cells called cholinergic neurons that produce acetylcholine, a chemical necessary for memory and thinking. Alzheimer's disease is linked to the buildup of beta-amyloid in the brain, which can damage neurons.
The researchers did tests on male and female mice and also studied the brains of older humans. They found that the connection between acetylcholine and harmful amyloid was weaker when estradiol was present. But when sex hormones were removed, this connection became stronger, which might increase Alzheimer's disease risk. This is especially important because estradiol levels drop in women after menopause.
The exact way estradiol affects beta-amyloid buildup has yet to be fully understood. It might have something to do with how the immune system responds to amyloid in the brain and how amyloid pathology changes when estradiol levels are low.
A neurologist and director of a centre specializing in Dementia, Alzheimer's Disease, and Neurocognitive Disorders in Santa Monica, CA, expressed a keen interest in a recent study's findings. According to this medical professional, the study offers valuable insights into sex-specific factors, particularly the influence of estradiol and cholinergic signalling in Alzheimer's disease.
These insights may have a significant impact on how healthcare providers assess and discuss Alzheimer's risk with female patients, particularly those in the perimenopausal age group.
In future discussions with female patients, healthcare providers may use these findings to offer a more personalized and informative approach to Alzheimer's risk assessment and management. Additionally, it may become crucial to consider a patient's hormonal status, including their menopausal stage and the role of estradiol, when evaluating their Alzheimer's risk. This emphasis on hormonal status could be especially relevant for perimenopausal women, as the study suggests that estradiol may influence the connection between cholinergic signalling and amyloid pathology.
To promote cognitive health and reduce Alzheimer's risk, particularly among those in the perimenopausal age range, healthcare providers should continue to underscore the importance of monitoring mental health and adopting lifestyle modifications. These modifications may include engaging in cognitive stimulation and maintaining a healthy diet, both of which have been linked to a reduced risk of Alzheimer's disease.
Mobi Doctor can provide valuable guidance and support in assessing Alzheimer's risk factors and offering personalized advice for cognitive health, especially for female patients in the perimenopausal age range.