Some older people can remember things just as well as peers who are nearly half their age. Scientists are calling them "super-agers" for their unique ability to stay sharp into old age.
Several months ago, researchers discovered at least one physical basis for these differences that has to do with the thickness of the outer layer of the super-agers' brains.
But in a small study published in October in the journal PLOS One, researchers took a look at whether there was a social side to these differences as well.
Sure enough, after studying 31 super-agers over age 80 as well as 19 cognitively average people of the same age, the scientists found that the super-agers tended to have significantly more satisfying, high-quality relationships than their normal peers.
"You don't have the be the life of the party, but this study supports the theory that maintaining strong social networks seems to be linked to slower cognitive decline," said Emily Rogalski, an associate professor of cognitive neurology at Northwestern's Feinberg School of Medicine and the lead author of the study, in a statement.
To arrive at their results, the researchers had all of the study participants complete a standard questionnaire designed to assess their general happiness and level of life satisfaction.
Despite getting similar scores overall on the questionnaire compared to their peers, the super-agers stood out in terms of how they evaluated their friendships with others.
"It's not as simple as saying if you have a strong social network, you'll never get Alzheimer's disease," said Rogalski.
"But if there is a list of healthy choices one can make, such as eating a certain diet and not smoking, maintaining strong social networks may be an important one on that list."
Super-ager brains are physically different than normal brains
Thanks to a spate of previous research, scientists already knew that the brains of super-agers were different - physically speaking - from normal brains belonging to people of the same age group.
They were slightly larger, especially in the outer cortex - the part of the brain that's made up chiefly of grey matter and is rich in neurons. What scientists didn't know until a few months ago, however, was whether that was because super-agers had bigger brains to begin with (perhaps from birth) or if they were somehow protected from the decay associated with ageing.
After comparing the brains of 24 super-ager men and women to those of 12 of their normal peers using MRI, the researchers found the answer came down to age-related shrinkage.
Over the course of their 18-month study, the scientists saw the brains of the average study participants atrophy at more than twice the rate of the brains of the super-agers.
Together, the two recent findings add several important new pieces to the puzzle of what makes a super-ager - and provides some insight into how age and social networks may affect the brains of regular people, too.
There are things the average person can do to stay sharp
As we age, our brain's grey matter - the stuff we rely on for seeing, hearing, processing emotions, 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 fibres (wiring, essentially) that carries information across different parts of the brain.
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 grey matter reserves run down.
If that doesn't happen, however, people experience the typical effects of ageing - 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.
This article was originally published by Business Insider.