Aging is something none of us can avoid. As we grow older, our bodies gradually lose their ability to repair damage, maintain tissue function and respond to stress. But aging is not caused by one single process. It is the result of many interconnected biological changes, including DNA damage, mitochondrial dysfunction, chronic inflammation and cellular senescence.
Cellular senescence is particularly interesting. Senescent cells are cells that have permanently stopped dividing but remain metabolically active. Instead of simply disappearing, they can release inflammatory molecules known as the senescence-associated secretory phenotype (SASP). When these cells accumulate, they can contribute to inflammation, tissue dysfunction and age-related diseases.
But there is another factor that changes significantly throughout our lives: sex hormones.
What happens to our hormones as we age?
Estrogen, progesterone and testosterone influence much more than reproduction. They are involved in the brain, bones, cardiovascular system, metabolism, immune function and tissue repair.
However, their levels change substantially with age.
In women, estrogen and progesterone decline markedly during the transition through menopause. In men, testosterone generally decreases more gradually, beginning earlier in adulthood.
This raises an interesting question:
Could declining sex hormones contribute directly to cellular aging and senescence?
Research increasingly suggests that the answer may be more complicated than simply yes or no.
Estrogen is more than a reproductive hormone
Among the hormones I explored, 17β-oestradiol (E2) showed some of the most consistent protective effects against cellular senescence.
Several studies suggest that estrogen can activate pathways involved in cell survival, stress resistance and regeneration.
For example, studies in human cells have shown that E2 can reduce markers of cellular senescence, increase proliferation and support telomerase activity. Other research has linked oestrogen to improved mitochondrial function and reduced inflammatory signalling.
Interestingly, there is also evidence that the relationship could work in both directions. While hormonal decline may contribute to cellular dysfunction, the accumulation of senescent cells may itself contribute to changes in ovarian function and hormone production.
This creates a fascinating possibility:
Hormonal decline and cellular senescence may form a feedback loop in which each process reinforces the other.
However, not every study supports a direct relationship. For example, research investigating estrogen deficiency and bone aging found that loss of estrogen and accumulation of senescent cells could occur through partly independent mechanisms.
This reminds us that aging is highly tissue- and context-dependent. And that is why hormone supplementation remains questionable as a strategy for slowing or reducing the processes of aging.
Progesterone: a much more complicated story
Progesterone was particularly interesting because its relationship with senescence appears much less straightforward.
In some situations, progesterone can promote a controlled senescence-like state. This can actually be beneficial. During the menstrual cycle and implantation, temporary senescence-related processes can contribute to tissue remodeling and communication with immune cells.
But uncontrolled or prolonged senescence can become harmful and contribute to inflammation and reproductive disorders.
Other studies suggest that progesterone signalling can protect cells from oxidative stress and senescence, particularly in reproductive tissues.
So progesterone cannot simply be labelled as either an “anti-aging” or “pro-aging” hormone.
Its effect appears to depend on where, when and how it acts.
And what about testosterone?
Testosterone is often discussed in relation to muscle mass, libido and male reproductive health. However, research suggests that it may also influence cellular aging.
Experimental studies have shown that testosterone can reduce senescence markers in vascular and cardiovascular cells and activate pathways associated with cell survival and stress resistance.
Testosterone and its derivative dihydrotestosterone (DHT) have also been investigated in relation to oxidative stress, cognitive function and tissue regeneration.
Interestingly, this again suggests a possible feedback relationship: aging can contribute to declining testosterone production, while low testosterone may also contribute to some aging-related changes.
Does this mean hormones are the answer to aging?
Not so fast.
Hormone replacement therapy can provide important benefits for appropriately selected individuals, particularly for managing symptoms and some consequences of menopause or confirmed hypogonadism.
However, hormonal therapy is not currently a universal anti-aging treatment.
The effects depend on the hormone, dose, timing, route of administration, tissue and individual health status. Hormonal therapies can also have risks, meaning that treatment should be individualized rather than viewed as a simple way to “restore youth.”
There is another fascinating direction in the field: senolytics, treatments designed to selectively remove senescent cells.
Early animal studies suggest that eliminating senescent cells may improve tissue function and, in some cases, partially restore aspects of hormonal function. This raises an entirely different question:
What if we do not only replace declining hormones, but also target the aged cells that may contribute to hormonal dysfunction?
So, can we use hormones to age better?
The research I explored suggests that sex hormones are much more deeply connected to aging biology than we traditionally think.
They can influence cellular survival, oxidative stress, inflammation, regeneration and senescence. At the same time, their effects are not universal, and sometimes even contradictory.
This is perhaps the most important lesson:
Healthy aging is unlikely to be controlled by one hormone, one pathway or one treatment.
Instead, we need to understand how hormones interact with cellular senescence, metabolism, inflammation, genetics and the environment, and how these relationships differ between individuals.
We are beginning to understand these connections, but we are certainly not at the point where we can say that hormonal manipulation is a safe way to stop or reverse aging.
And perhaps that is what makes this field so exciting.
The future of healthy aging may not be about finding a single “anti-aging” treatment. It may be about understanding the complex biology of aging well enough to know which processes should be prevented, which should be supported, and which should simply be allowed to happen.
References
López-Otín, C., Blasco, M. A., Partridge, L., Serrano, M., & Kroemer, G. (2023). Hallmarks of aging: An expanding universe. Cell, 186(2), 243–278. https://doi.org/10.1016/j.cell.2022.11.001 https://www.cell.com/cell/fulltext/S0092-8674(22)01377-0
Ng, M., & Hazrati, L.-N. (2022). Evidence of sex differences in cellular senescence. Neurobiology of Aging, 120, 88–104. https://doi.org/10.1016/j.neurobiolaging.2022.08.014 https://pubmed.ncbi.nlm.nih.gov/36166919/
Cheng, J., Zhao, Z., Wang, L., Wen, J., Miao, Y., & Wu, J. (2025). The Anti-Senescence Effect and Mechanism of 17β-Estradiol on Pelvic Organ Prolapse Derived Fibroblasts. BIOCELL, 49(2), 335–348. https://doi.org/10.32604/biocell.2025.059573 https://www.sciencedirect.com/org/science/article/pii/S0327954525000143
Farr, J. N., Rowsey, J. L., Eckhardt, B. A., Thicke, B. S., Fraser, D. G., Tchkonia, T., Kirkland, J. L., Monroe, D. G., & Khosla, S. (2019). Independent Roles of Estrogen Deficiency and Cellular Senescence in the Pathogenesis of Osteoporosis: Evidence in Young Adult Mice and Older Humans. Journal of Bone and Mineral Research : The Official Journal of the American Society for Bone and Mineral Research, 34(8), 1407–1418. https://doi.org/10.1002/jbmr.3729 https://pubmed.ncbi.nlm.nih.gov/30913313/
Faubion, L., White, T. A., Peterson, B. J., Geske, J. R., LeBrasseur, N. K., Schafer, M. J., Mielke, M. M., & Miller, V. M. (2020). Effect of menopausal hormone therapy on proteins associated with senescence and inflammation. Physiological Reports, 8(16), e14535. https://doi.org/10.14814/phy2.14535 https://pubmed.ncbi.nlm.nih.gov/32857481/