Think about the people in your life who are 65 or older. Some of them are experiencing the usual mental difficulties of old age, like forgetfulness or a dwindling attention span. Yet others somehow manage to remain mentally sharp. My father-in-law, a retired doctor, is 83 and he still edits books and runs several medical websites.
Why do some older people remain mentally nimble while others decline? “Superagers” (a term coined by the neurologist Marsel Mesulam) are those whose memory and attention isn’t merely above average for their age, but is actually on par with healthy, active 25-year-olds. My colleagues and I at Massachusetts General Hospital recently studied superagers to understand what made them tick.
Our lab used functional magnetic resonance imaging to scan and compare the brains of 17 superagers with those of other people of similar age. We succeeded in identifying a set of brain regions that distinguished the two groups. These regions were thinner for regular agers, a result of age-related atrophy, but in superagers they were indistinguishable from those of young adults, seemingly untouched by the ravages of time.
What are these crucial brain regions? If you asked most scientists to guess, they might nominate regions that are thought of as “cognitive” or dedicated to thinking, such as the lateral prefrontal cortex. However, that’s not what we found. Nearly all the action was in “emotional” regions, such as the midcingulate cortex and the anterior insula.
My lab was not surprised by this discovery, because we’ve seen modern neuroscience debunk the notion that there is a distinction between “cognitive” and “emotional” brain regions.
This distinction emerged in the 1940s, when a doctor named Paul MacLean devised a model of the human brain with three layers. An ancient inner layer, inherited from reptiles, was presumed to contain circuits for basic survival. The middle layer, the “limbic system,” supposedly contained emotion circuitry inherited from mammals. And the outermost layer was said to house rational thinking that is uniquely human. Dr. MacLean called this model “the triune brain.”
The triune brain became (and remains) popular in the media, the business world and certain scientific circles. But experts in brain evolution discredited it decades ago. The human brain didn’t evolve like a piece of sedimentary rock, with layers of increasing cognitive sophistication slowly accruing over time. Rather (in the words of the neuroscientist Georg Striedter), brains evolve like companies do: they reorganize as they expand. Brain areas that Dr. MacLean considered emotional, such as the regions of the “limbic system,” are now known to be major hubs for general communication throughout the brain. They’re important for many functions besides emotion, such as language, stress, regulation of internal organs, and even the coordination of the five senses into a cohesive experience.
And now, our research demonstrates that these major hub regions play a meaningful role in superaging. The thicker these regions of cortex are, the better a person’s performance on tests of memory and attention, such as memorizing a list of nouns and recalling it 20 minutes later.
Of course, the big question is: How do you become a superager? Which activities, if any, will increase your chances of remaining mentally sharp into old age? We’re still studying this question, but our best answer at the moment is: work hard at something. Many labs have observed that these critical brain regions increase in activity when people perform difficult tasks, whether the effort is physical or mental. You can therefore help keep these regions thick and healthy through vigorous exercise and bouts of strenuous mental effort. My father-in-law, for example, swims every day and plays tournament bridge.
The road to superaging is difficult, though, because these brain regions have another intriguing property: When they increase in activity, you tend to feel pretty bad — tired, stymied, frustrated. Think about the last time you grappled with a math problem or pushed yourself to your physical limits. Hard work makes you feel bad in the moment. The Marine Corps has a motto that embodies this principle: “Pain is weakness leaving the body.” That is, the discomfort of exertion means you’re building muscle and discipline. Superagers are like Marines: They excel at pushing past the temporary unpleasantness of intense effort. Studies suggest that the result is a more youthful brain that helps maintain a sharper memory and a greater ability to pay attention.
This means that pleasant puzzles like Sudoku are not enough to provide the benefits of superaging. Neither are the popular diversions of various “brain game” websites. You must expend enough effort that you feel some “yuck.” Do it till it hurts, and then a bit more.
In the United States, we are obsessed with happiness. But as people get older, research shows, they cultivate happiness by avoiding unpleasant situations. This is sometimes a good idea, as when you avoid a rude neighbor. But if people consistently sidestep the discomfort of mental effort or physical exertion, this restraint can be detrimental to the brain. All brain tissue gets thinner from disuse. If you don’t use it, you lose it.
So, make a New Year’s resolution to take up a challenging activity. Learn a foreign language. Take an online college course. Master a musical instrument. Work that brain. Make it a year to remember.
By Lisa Feldman Barrett for the New York Times