Scientists have discovered why some people are 'super-agers'

So much for not being able to teach an old dog new tricks.

Research has shown that some older people stay sharp into old age and retain the ability to recall personal experiences with just as much accuracy as their middle-aged peers. The brains of these so-called "super-agers" look distinct, too: Their gray-matter-rich outer layer, or cortex, is thicker.

For a new 18-month study, the results of which were published April 4 in the Journal of the American Medical Association, researchers investigated whether these keen individuals simply start out with bigger brains or if, instead, they are somehow protected from time's slow erosion of the brain's gray matter.

The researchers screened more than 1,000 people, less than 5% of whom qualified as bona-fide super-agers. They then compared the brains of those 24 men and women (all of whom were over 80 years old) to the brains of 12 similarly-aged "cognitively average" adults using MRI technology.

It turns out the super-ager brains may not initially be any bigger or more robust. Instead, the researchers discovered that the brains of the average study participants were atrophying at more than twice the rate of the super-agers' brains over the 18-month study window. The new paper therefore suggests that these rare individuals are shielded from the normal age-related atrophy process that wears away the neuron-dense outer layer of our brains.

This finding adds an important new piece to the puzzle of what makes a super-ager — and provides some insight into how age affects the brains of regular people, too.

How to protect an aging brain

As we age, our brain's gray matter — the stuff we rely on for seeing, hearing, processingemotions, exerting self-control, learning new information, and more — shrinks and degrades. So too does our brain's white matter, which contains the complex web of twisting fibers (wiring, essentially) that carries information across different parts of the brain.

Interestingly, a small 2014 study published in the journal Nature Communications suggested that in some older people, white matter may act as a sort of backup generator that can fire up when gray matter reserves run down.

If that doesn't happen, however, people experience the typical effects of aging — fuzzier memory, a harder time paying attention, and difficulty learning new skills.

Super-agers and people gifted with extra-flexible white matter are rare, but some research suggests there are things the average person can do to stay keen with age as well. These include getting regular exercise, maintaining strong bonds with friends or family, quitting or not starting smoking, and learning new things or being intellectually challenged. So if you've been meaning to meet up with some old friends or have been putting off joining that yoga studio, there's no time like the present.