Infertility due to aging is a tough problem to solve. Ovaries start with a specific reserve of eggs. As you get older, this reserve diminishes until, eventually, it is completely gone. What treatments exist can be expensive and difficult and, in the case of egg freezing, require years of planning.
Does this really have to be the case? Rapamycin, a bacterial compound prescribed to organ-transplant patients, is being tested in various contexts as an antiaging treatment. It may be able to extend fertility—and stave off menopause to boot. Numerous outlets are reporting that a weekly dose of the drug could specifically provide a whopping five extra years of fertility, a very promising development if true.
Unfortunately, the evidence we have right now simply isn’t convincing. It’s possible that taking rapamycin could help with fertility, but we have no real idea if it does.
Rapamycin has been a mainstay of the antiaging crowd for over a decade. Early studies in the late 2000s showed that it could potentially keep lab mice alive for quite a bit longer with few noticeable downsides, a discovery that has led to an expanded range of research on rodents. In mice, rapamycin has proved to reduce the risk of cancer and heart disease, enhance memory, and even improve the immune system. There’s some evidence that, when combined with exercise therapy, rapamycin can mitigate age-related loss of muscle in mice. That’s quite alluring—muscle loss causes so many of the issues we see in older humans.
When it comes to fertility, there’s even some published data showing that rapamycin can slow the diminishment of the ovarian reserve of—again—mice in labs. Although it’s still early, this data is seen by some as encouraging because there are currently few things you can do to improve fertility if your ovarian reserve is low.
The problem with all this data is that mice aren’t people. In humans, we have essentially no evidence that rapamycin can do any of the magical stuff it seems to do in rodents. The current trials of rapamycin for aging-related issues in people are limited to a handful of studies with tiny samples—and major issues. One such study, looking at whether rapamycin cream could improve skin markers of aging, had only 36 participants. Nineteen of them dropped out, leaving the study almost entirely useless as evidence. It’s not that rapamycin definitely isn’t useful as an antiaging compound. It’s that we just don’t have the evidence yet about whom it’s useful for, how, and in what doses, or if those results in mice will pan out in humans at all. (This has not stopped companies from marketing and selling it as such.)
Yes, scientists are looking into rapamycin’s effects in humans. When it comes to ovarian aging, all of the recent hype is based on research called the Vibrant study. This trial is randomizing women to receive either rapamycin or a placebo to examine whether the drug can slow the decline of the ovarian reserve over time, exactly the thing that would be really exciting to know.
The issue is that the news reports are based on very early results of the trial, reported on in July by the Guardian. The authors aim to eventually recruit 1,000 women, but preliminary data discussed in broad terms with journalists involved just 34 study participants, all under the age of 35. “The results of this study—the first in human history—are very, very exciting,” a co-lead of the study told the Guardian. “It means that those with age-related fertility problems now have hope when before, they didn’t.”
It’s entirely possible that these initial results are as spectacular as the researchers say they are. And it’s possible that this further research, with more women included, will bear out the impressive benefits of rapamycin for fertility. It’s also possible that the final results of this study will show no improvements at all. Based on the study registration, which was last updated in July, the researchers haven’t yet finished recruiting and won’t report final results for at least a year. And even if those results support the findings that they’ve reported so far, and even if the researchers go on to do more trials, this particular study will still look at only 50 people in total. That’s not a large enough sample size from which to draw firm conclusions about rapamycin and ovarian reserves.
It is simply difficult to assess at this stage. If you’re into following the blow-by-blow process of how science works, perhaps hearing researchers get excited about their work is interesting. But if you’re an average woman contending with the effects of aging, it’s tough to see how this is useful. (At the very least, the research will take a while.)
Why be a pessimist about this? We hear a lot about promising early results, but those results rarely pan out. Most of the hopeful messages you see in the news end up abandoned either because no one is interested in funding what, at some point in animal studies or small human studies, ends up looking like a dead end or because the drugs simply fail in larger trials to show the benefits that people thought they might have. (And those stories don’t usually make the news.)
It’s a particularly big problem for antiaging studies because anything that could possibly, maybe treat the symptoms of age is a huge story. Any drug, supplement, relaxation technique, or even mindset that could potentially keep us younger for longer is something that most of the world is immediately interested in. But these are very hard problems to fix, and it’s extremely unlikely that any news story is going to be reporting on a treatment that, in the end, really does work, simply because those treatments are so rare.
It’s certainly possible that rapamycin will turn out to extend fertility in women by years or even decades. Perhaps it will also end up having all of the impressive benefits in humans as are currently claimed for mice. But realistically, there’s just not much reason to believe that the drug works. What would convince me? Large and robust clinical trials that have been completed and published in peer-reviewed journals.