When optimists assure us that age is just a state of mind, even they know they don’t mean it literally. But as with virtually every other body function, it may be that aging is controlled by our brains. In a study published this month in the journal Nature, researchers at the Albert Einstein College of Medicine in New York discovered that the aging process in mice can be controlled by manipulating a molecule called NF-kB in the hypothalamus—a nut-sized part of the brain that has long been known to control many other things like body metabolism and growth. The NF-kB is a signaler affecting the levels of a hormone called GnRH, which has been linked to neuron regeneration. By stimulating NF-kB the scientists could accelerate the aging of the mice, but by blocking the NF-kB and injecting the mice with additional GnRH they were able to slow the aging process and extend the lifespan of the mice by as much as 20%. And it wasn’t only that the mice lived longer, but they were less susceptible to age-related health problems, including chronic conditions related to inflammation.

A study from Yale University earlier this year found that a single gene in mice, the Nogo Receptor 1, appeared to be the switch controlling the maturation of the mouse brain. With the Nogo receptor chemically switched off, the brains of older mice re-acquired the ‘plasticity’ of adolescent mouse brains, enabling better learning, less mental decline, and perhaps even better healing from brain damage. (Did the re-adolescent mice start giving attitude, I wonder?)

Of course, this is another research story Of Mice And Men—it will be years before we can expect to find any of these methods translated for humans. But it’s the job of SF writers to predict from current trends. What will we do when people can live much longer lives?

Say we routinely live an extra forty or fifty years—will we be willing to add those years to our working lives? Or will we expect our retirement to somehow exceed our money-earning years?

How will younger people rise within company structures if all of the plum executive positions are locked up by elders who refuse to go away? What would motivate a young worker in a scenario like that? And then there’s the question of innovation: wouldn’t the oldsters with the power be inclined to maintain the status quo? The same would almost surely be true of government. Slowing aging might put the brakes on progress, both technical and social. And, especially if the age-retarding treatments were expensive, the power gap between rich and poor would become ever more firmly entrenched.

The costs of a longer-lasting population would also be high, financially and ecologically. Our economies can’t afford more people who aren’t producing goods and wealth, and our planet can’t sustain many more mouths to feed. Maybe from the beginning of our working lives it would be mandatory to set aside ten or twenty percent of our income for investments to support us in our later years. Maybe, like China, governments would be forced to regulate the number of offspring we have. Maybe you would be allowed to get the longevity treatment only if your children agreed to be sterilized and remain childless.

The Fountain of Youth sounds like one giant can of worms to me.