The Difference in Alzheimer's Between Men and Women

Written By: Alaina Yan

Alzheimer's, a neurodegenerative brain disorder, has been found to be twice as prevalent in women as men. Many have assumed that this difference is due to women living longer. However, there are many key differences between men and women’s brains as they age. 

To begin, men’s brains shrink faster than that of females. While surprising as they experience a lower rate of Alzheimer's diagnosis, men lose the grey and white matter of their brain faster than females. In fact, females’s brains decline in fewer regions and have minimal change in the thickness of their cortex, the outer layer of the cerebrum.

(Ravndal et al., PNAS, 2025)

Another key difference between females and males are the sex hormones the brain releases. For females, progesterone and estrogen are released. For males, testosterone is the dominant hormone. Drops in progesterone and estrogen are responsible for menopause in middle-aged women. As this drop in hormones impacts the brain at an age where women are susceptible to developing Alzheimer’s, scientists began to research whether the dominant hormone does have an impact. Buckley, an investigator at Massachusetts General Hospital, realized that a woman receiving hormone replacement therapy at age 70 had significantly higher amounts of tau accumulation in her brain. A key component of Alzheimer's, this tau accumulation confirmed that hormones do have an impact on Alzheimer's development. However, Buckley also discovered that the timing of HRT or any hormone change plays a role in whether the impact is negative or positive; young women who took HRT had less cognitive decline while women over 65 experienced more cognitive decline. 

Males have XY chromosomes while females have XX chromosomes

The third difference between female and male brains may be the most obvious: the X and Y chromosomes. While men have one X chromosome and one Y chromosome, women have two sets of X chromosomes. As X chromosomes have more vital genes, women have one of their X chromosomes silenced and inactive. However, this silencing act is not perfect. As a result, genes for the immune system and regulating brain structure will be altered. While still uncertain in studies, the difference in these regulating genes could be a reason for the larger female Alzheimer's population.

Citations:

Cassella, Carly. “Male Brains Shrink Faster than Female Brains, Study Finds.” ScienceAlert, 18 Oct. 2025, www.sciencealert.com/male-brains-shrink-faster-than-female-brains-study-finds. Accessed 28 Nov. 2025.

DeMarco, Stephanie. “Sex Differences in the Brain Get down to the Molecular Level.” The Scientist, The Scientist Magazine, 19 Nov. 2025, www.the-scientist.com/sex-differences-in-the-brain-get-down-to-the-molecular-level-73768. Accessed 28 Nov. 2025.

Powell, Alvin. “Why Are Women Twice as Likely to Develop Alzheimer’s as Men?” Harvard Gazette, 7 July 2025, news.harvard.edu/gazette/story/2025/07/why-are-women-twice-as-likely-to-develop-alzheimers-as-men/.