Dementia continues to be one of the biggest global public health challenges, with women almost twice as likely as men to develop Alzheimer’s disease and other forms of dementia. While hormones like testosterone have long been thought to play a role in brain function as we age, the relationship has remained unclear—until now.
A large-scale study led by researchers Yanqing Zhao and colleagues, recently published in Clinical Endocrinology, has shed new light on how sex hormones could shape dementia risk in both men and postmenopausal women.
What Did the Study Find?
Using data from over 300,000 participants in the UK Biobank, the researchers measured levels of testosterone and sex hormone binding globulin (SHBG)—a protein that controls the availability of sex hormones in the body. They then tracked dementia diagnoses over an average of 12 years.
Here’s what they uncovered:
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Men with higher free testosterone levels had a significantly lower risk of developing all-cause dementia and Alzheimer’s disease. Those in the highest quintile of free testosterone had a 37% lower risk of dementia compared to men with the lowest levels.
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Conversely, men with higher SHBG levels were more likely to develop dementia. High SHBG was linked to a 47% increased risk of all-cause dementia.
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Among postmenopausal women, moderately higher free testosterone levels also appeared protective. Women in the fourth quintile had a 16% lower risk of dementia.
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Higher SHBG levels in women were similarly associated with a higher risk of both dementia and Alzheimer’s disease.
Why Does This Matter?
These results suggest that maintaining balanced sex hormone levels, particularly higher free testosterone and lower SHBG, could be an important factor in reducing dementia risk for both men and postmenopausal women. Although the study does not prove causation, it provides strong evidence that hormone levels are tied to long-term brain health.
The Road Ahead
The researchers emphasize that more studies are needed to understand whether adjusting hormone levels could directly prevent dementia or slow its progression. For now, this study highlights the potential for hormone health to play a bigger role in future dementia prevention strategies.
This blog post is based on the study: “Sex Hormones and Risk of Incident Dementia in Men and Postmenopausal Women” by Yanqing Zhao et al., published in Clinical Endocrinology, May 2025.
