EExtending the human lifespan is a multibillion-pound industry and has been hailed as the most fascinating scientific challenge in modern history. But as a drug to achieve long life is ever discovered, one thing seems certain: it is highly unlikely that it will work on women – and almost inconceivable that it will work on mothers.
That’s because, experts say, cages in laboratories around the world are filled with white mice who share a striking similarity: They’re all male.
This is a serious problem, said Dr Steven Austad, a biologist and the author of the bestseller Methuselah’s zoobecause the gender differences between rodents are significant – and the differences between virgin female mice and mice that have given birth are even greater.
Ignoring these differences meant, according to Austad, that a drug tested only on male mice was “highly unlikely” to work on females, and it was “more or less a complete fluke” if it also worked on women who have given birth. .
“It’s a big problem,” he said. “The lack of in-depth research on female mice means that we only know what works on male mice to the complete exclusion of female mice.”
About 75% of the drugs that extend lifespan in mice only work on males: the drugs were developed on male mice and then later tested on both sexes, only to discover that the females did not respond.
But while researchers know female mice respond differently to drugs than males, there have been no studies on separate interventions that might help women live healthier, longer lives.
A sobering example is from 1993, when the first papers are out methionine diets has been published. The results were astonishing: the diet was found to extend life by more than 40% in rats. Several follow-up studies were conducted throughout the 1990s, all showing the same astonishing results.
It took 12 years before it was pointed out that the rats in every single study were exclusively male, and that perhaps it would be a good idea to test on females as well. When the study was redone with females, it found that the life-sustaining diet for males caused a number of the females to die early.
Jennifer Garrison, an assistant professor specializing in reproductive health and ovarian aging at the Buck Institute for Research on Aging, said there is a “really profound sex bias in biomedical research and in clinical research going back as long as we The male body has been biology’s baseline for the past 100 years, and if you don’t study female bodies, you’re never going to learn anything about it.”
Garrison criticized virtually all longevity research as failing women because, she said, even the few studies that included virgin female mice ignored the times those mice were in their reproductive cycle.
“You absolutely have to take that into account because women’s physiology is so different over the cycle,” she said. “If you don’t look at where they are in their cycle, then it’s like you have a blindfold on.”
Another problem with longevity research, she said, was in the extremely rare cases where female mice were properly studied, they were specifically selected to never give birth, thereby ignoring the multiple and permanent effects that birth had on female physiology. .
According to a paper by Austad, which will soon be published in the journal Limits of Agingone of the reasons there hasn’t been more progress in extending women’s healthy longevity is because researchers aren’t interested in studying the question.
“It’s so striking that it begs us to investigate it more deeply, but no one is paying attention to this and it just keeps happening,” said Austad, the founding director of the University of Alabama at Birmingham Nathan Shock Center of Excellence in the Basics Biology of aging.
“There was a great study that came out very recently did what most studies do: it showed an experiment using mostly male mice, then it hid a cursory look at females deep in the small print, and then both sexes were combined in the results. There was never a look or mention that there may or may not be a gender difference.
He said more should be spent trying to understand these gender differences “so we can develop drugs that benefit both sexes. Women deserves to be taken seriously. Science really needs to change to honor that.”
