Читать книгу Brain Rules for Aging Well - John Medina - Страница 13

My favorite kind of pain is in my stomach when my friends make me laugh too hard.

—Anonymous

At some point, you have to realize that some people can stay in your heart but not in your life.

—Sandi Lynn, author of Forever Black

HERE’S A SENTENCE YOU probably don’t want to hear from Dad an hour after your wedding: “I’ll tell you what. If it lasts more than a year, I’ll give you a hundred bucks.”

Unfortunately, that’s exactly what happened to Karl Gfatter, a story he enthusiastically relates in a nursing home, wheelchair bound now, his loving bride at his side. And Dad had to pay up, probably many times over, for Karl and Elizabeth have stayed together for more than seven decades. Karl related this comment to the local media, who dropped by as he and Elizabeth were celebrating a recommitment ceremony in honor of their seventy-fifth wedding anniversary. They were surrounded by residents, staff, clergy. And rice. Plus lots of joy, smiles, and even some tears, creating the feeling you’d just walked onto the set of It’s a Wonderful Life. Both were radiant, bright as buttons. “We eloped because they didn’t want us to get married yet. They said we were too young!” Elizabeth laughed.

What Karl and Elizabeth may not know is that having a long marriage—and a room full of friends—is helping to keep their brains young. Friendships, and the social activities that surround them, are the major focus of this chapter. We’ll discuss the cognitive power of maintaining friendships over many years, along with the opposite: loneliness. Then we’ll dance our way toward a surprisingly beneficial brain booster.

Socializing: vitamins for the brain

You’d have a hard time finding someone more socially active—and intellectually lively—than wealthy heiress and arts patron Brooke Astor. By the year 2000, she was New York royalty, married to a man whose father actually died on the Titanic. Along with three of her closest friends—fashion publicist Eleanor Lambert, former opera singer Kitty Carlisle, and fashion designer Pauline Trigère—Brooke tore through a social schedule that required four changes of clothing a day. Lunch at a downtown café, then a board meeting at the Museum of Modern Art (she was a trustee), an evening concert at Carnegie, followed by a benefit dinner, ending with late drinks, returning home in a comet tail of paparazzi flashbulbs.

Brooke kept a social schedule that could leave a twentysomething personal secretary exhausted. And did—which is in great contrast to the physical ages of the women in this smart, lively quartet. Kitty, the youngest of the bunch, turned ninety that year. Pauline was ninety-one; Eleanor, ninety-six. Brooke was ninety-eight years old.

Did their age, social activity, and intellectual vigor have anything to do with one another? The answer, to the acclaim of elderly partygoers everywhere, is yes. Social interactions are like vitamins and minerals for aging brains, with ridiculously powerful implications. Even socializing over the Internet provides benefits.

The studies are anchored in the safe harbor of peer-reviewed research. The first set of studies established a solid correlation between social interactions and cognition. Researcher Bryan James, an epidemiologist with the Rush Alzheimer’s Disease Center, assessed the typical cognitive function and social interactivity of 1,140 seniors without dementia. He scored their social interactivity, then measured their rate of global cognitive decline over a twelve-year period. For the group that socialized the most, the rate of cognitive decline was 70 percent less than for those who socialized the least.

Other researchers focused on specific types of cognition and found virtually the same thing. One famous study looked at rates of memory decline in social isolates versus social butterflies, examining a staggering 16,600 people over six years. Memory decline of the Brooke Astors was half that of the shut-ins. A flurry of other findings confirmed a robust correlation between social interactions and cognitive health.

Even better, the next set of studies looked at causation, not just correlation. They measured people’s baseline cognition, introduced some form of socialization, then remeasured cognition. One intervention showed a cognitive boost in processing speed and working memory with as little as ten minutes of social interaction. Like a public television fund-raiser, data linking socialization with brain power turns out to be remarkably persistent.

The interactions don’t have to be within a long-term relationship, and they don’t necessarily refer to the number of friends one has. Researchers who study this stuff use words like “positive social interactions” (generally associated with the release of dopamine in the brain), “negative social interactions” (generally associated with hormones such as catecholamines and glucocorticoids, released in response to stress), and “social exchanges” (to describe interactivity). I’m going to use the word “relationships” more often to keep things friendly. But if you have social interactions that are positive—whether deep or momentary, with one person or dozens—benefits accrue.

What about the digital world? Does the social interaction have to be in person? Researchers realized long ago that the Internet might provide a perfect way for socially isolated, mobility-challenged seniors to interact with others. The rise of video chats created a terrific experimental test bed. Could people increasingly tethered to home still get a brain lift?

The answer, welcome as a Rothko retrospective, was again yes. One experiment involved people eighty years and older, measuring a baseline for executive function skills and an aspect of language ability that’s related to executive function. Executive function (EF) is a behavioral gearbox mostly housed in the prefrontal cortex, an important region located right behind your forehead. EF includes cognitive control (such as the ability to shift attentional states), emotional regulation (such as the ability to manage your anger), and short-term memory. The researchers got baseline EF scores, then installed a video-chat program for each person and proceeded to hold conversations with the octogenarians, averaging thirty minutes per day for six weeks. Four and a half months later, their brains were retested.

Researchers observed large improvements in both executive function and language skills. The scores leapfrogged over controls who spoke for thirty minutes by phone only. This is consistent with other data suggesting that the better you simulate actual human contact, the richer the social experience becomes. Video chat is not perfect, but for those without the option of regular human contact, it’s a godsend.

These findings are worthy of a J. D. Power award for senior citizen customer satisfaction. Which means you should get out your social calendar, iron your best clothes, and go run a board meeting. Or visit a museum. The answer to the question “Does socialization really decrease the rate of cognitive decline?” is a robust and hearty “Yes.”

How exactly does the buoyant power of socialization work? Two main ways: it reduces stress, which helps maintain not only the body’s general health but specific aspects of the immune system, and it’s a workout for the brain.

More parties, less flu

The more positive social interactions you have, the lighter your allostatic load becomes, as neuroendocrinologist Bruce McEwen would put it. He’s the researcher who came up with the concept of “allostatic load.” Allostatic load is the aggregate effect of stress on your body’s capability, including brain capability, through time. The more stress you encounter, the bigger the load (and the greater the damage). Consider stress metaphorically: the stresses in life are oceanic waves, and your body is a cliff. The more waves that crash onto the cliff, the greater the erosion, and the more severe the total effect. Allostatic load is the measure of your body’s deterioration, in response to the lifelong waves of stress you experience.

Less stress is important particularly for the immune system. The immune system naturally becomes compromised as you age, but the more stressed you are, the greater risk you run of weakening parts of the immune system. We even know why. One critical arm of the immune system involves a group of cellular warriors known as T-cells. These cells play critical roles in wound healing (like when you get a cut) and recovering from infectious diseases (like when you get colds and flus). Stress hormones like cortisol—at the high levels you experience when you’re in a bad marriage or otherwise chronically stressed—actually kill T-cells. Your wounds heal at a rate 40 percent slower if you’re in a high-hostility marriage than in a low-hostility one. And you get more colds. Says elderly-care expert Gary Skole: “Those elderly folks who get out and interact and spend more time with people during cold/flu season actually get fewer colds and illnesses than those who spend most of their time alone.”

These data serve to underscore the growing link in the scientific literature between positive interactions, stress reduction, and longer life. No doubt Karl and Elizabeth are right now busy nodding their heads. And Karl’s dad is probably rolling around in his grave.

A workout for your brain

One of the reasons why social interactions are so good for you is that they take so much energy to maintain, consistently giving your brain a bona fide workout. Case in point is a clip from the movie When Harry Met Sally. The scene is where Sally (Meg Ryan) asks Harry (Billy Crystal) to come over for some major-league consolation: Sally’s ex has decided to marry someone else. Through tears and sobs and gobs of tissues, Sally tells Harry, “All this time, I’ve been saying that he didn’t want to get married. But the truth is, he didn’t want to marry me.” Harry, bless him, attempts his best lifeboat impression, although by now Sally is nearly drowning in a cocktail of saltwater and snot. “I’m difficult!” she blubbers. Harry counters thoughtfully: “Challenging.” Sally sobs, “I’m too structured, I’m completely closed off!” Harry shrugs: “But in a good way.”

With unexpurgated grief in Sally’s case and measured restraint for Harry, the amount of energy the two exude in this delightful scene is extraordinary. It illustrates something scientists have known for years: flesh-and-blood friendships take work. And that’s because social interactions take work. And by work, I mean in a biochemical, energy-expending kind of way. Some researchers believe social interactions are the most complex, energy-intensive jobs your brain can consciously perform. Every time it intermingles at a cocktail party or consoles a friend, the organ experiences the cognitive equivalent of an aerobic workout.

Says Chelsea Wald, writing in Nature magazine: “[Researchers] suspect that the cognitively demanding act of socializing can actually build up the brain—like exercising builds up muscles. This ‘brain reserve’ may then act as a buffer against functional loss, even in the face of conditions such as Alzheimer’s disease.”

Suppose you were the scientist hypothesizing that social interactions are cognitive calisthenics. You might predict that the more social interactions you have, the more you exercise the brain regions responsible for those interactions. You might further hypothesize that the neural tissue will become bigger and stronger or more active as a result. You might guess there would even be bleed-through effects, given that the job descriptions of most brain regions are hopelessly intertwined with those of other regions, all moonlighting to produce a broad array of functions. From cell to behavior, you can measure whether growth is occurring.

And scientists have. Though the data are largely correlative, growth is exactly what they find.

Let me pause for a moment to define a few terms: social activities, social networks, and social cognitions. Researchers define these terms much as the public does, especially if that public uses words like “neurological substrates.” Social activities are the actual experiences you have with others, whether going out on a boat or going out on a date. Social networks are the number of people with whom you willingly have those experiences. Close friends and family generally populate these activities. Social cognitions are the psychological (and by implication, neurological) substrates you use to interact with others when socializing.

On to the studies showing that the brain is being exercised.

The more social relationships you maintain, the bigger the gray matter volume in specific regions of your frontal lobe. Which means that relationships are to the frontal lobe what milk shakes are to your waistline. The frontal lobe is the large region right behind your eyes, running to the middle of your head (where a headband would sit). This region is associated with a cognitive gadget called mentalizing, or Theory of Mind. Mentalizing is the ability to discern the mental states of others, particularly their motivations and intentions. It’s as close to mind reading as your brain will ever get. Mentalizing abilities play a powerful role in establishing and maintaining social relationships, as you can imagine.

The frontal lobe is also responsible for helping you predict the consequences of your own actions. It helps you suppress socially inappropriate behaviors and even make comparative decisions. For many reasons, these are important regions to keep fat and happy.

The amygdala, a little almond-shaped nodule dangling just behind each ear, is involved in processing your emotions. It too is affected by levels of social activity. The higher the overall number of (and the greater the variability in) the types of relationships you maintain, the bigger your amygdala becomes. These aren’t small changes. If you triple the number of people in your social network, you double the volume of your amygdala. Wondering how you’d keep up with all those people? While you maintain your closest relationships with five people at a time, researchers find, you can have meaningful relationships of varying quality with an additional 150 people. Think of it as rings of relationships.

Social activity also affects a region called the entorhinal cortex, which helps you recall important things like your first kiss. This romantic bundle of nerves, which also helps process other types of memories (and many types of social perceptions), is located in the temporal lobe, the brain regions closest to your eardrums.

Given the rise of the Internet, does it matter which kind of social network is being measured, silicon- or carbon-based? It does. For example, gray matter changes in non-amygdalar regions (like the frontal lobe and entorhinal cortex) occur only with flesh-and-blood interactions. In contrast, density changes in the amygdala are specifically associated with the size of both Web-based social networks and the number of face-to-face social interactions. The reasons for these differences, extraordinary as they may sound, are not known.

Not all social interactions are created equal, however. You don’t have to look any further than a typical day in an American office, populated by dysfunctional management, for an example.

The boss from hell

The boss wore his unpleasantness like a purity ring on his middle finger. He publicly announced the contents of private meetings to his entire forty-person staff. He slapped the hand of a loyal employee who had worked for the company for forty-four years. When that employee asked for time off to go to the hospital where her daughter had suddenly been admitted, the boss replied, “What are you going to do, hold her hand?”

I describe this narrative, one of many stories online chronicling chronically bad working relationships, to counter an impression you might be getting from this chapter: that every relationship provides neurological benefit. The truth is just the opposite. You can have many relationships with people, but if they’re negative, they’re unhealthy. Studies show that it’s not the overall number of interactions that benefit health, but the net quality of the individual interactions. According to researchers from the University of North Carolina at Chapel Hill: “Social support and strain, which measured qualitative characteristics of social connections that are distinct from relationship quantity, mattered more for physical health in mid-adulthood, and continued to have impacts in late adulthood.”

Behavioral labs are coming up with all kinds of dos and don’ts for relationships. Interactions burdened with competitive one-upmanship provide no cognitive benefit at all. Relationships with people who are emotionally controlling, meddlesome, or consistently verbally aggressive (like that aforementioned boss) are worth limiting, if not ending altogether.

Drop the ego

What’s the secret to a good interaction for your brain? It’s a willingness to consistently take the other person’s point of view, actively seeking to understand a different perspective. You may agree with the other person or you may not, but the effort transforms casual conversation into meaningful brain food. If that sounds like Theory of Mind stuff we’ve been talking about, you are right on the research money. It’s also a scientifically nice way of saying: stop being so self-centered. This advice, by the way, is just as healthy for people much younger than your average Social Security recipient. Regularly engage people, and your brain will thank you at any age.

You can create an environment conducive to quality relationships. Social psychologist Rebecca Adams summarized how in a New York Times interview a few years back, if you cultivate the following:

• “repeated, unplanned interactions,” spontaneously rubbing shoulders with good friends

• “proximity,” living close by to friends and family members so those shoulders are available for rubbing

• “a setting that encourages people to let their guard down”

Not surprisingly, Adams relates, most of our tightest friendships initially form in college, where these conditions are met by design.

It’s best to have friends of all ages—including kids. That notion may transcend our culture’s perspective, but not our culture’s data. The more intergenerational relationships older people form, the higher the brain benefit turns out to be, especially when seniors interact with elementary-age children. It reduces stress, decreases rates of affective disorders such as anxiety and depression, and even lowers mortality rates.

There are probably many reasons for these findings. Young people always have different perspectives from their elders. That means regular exposure to virtually anyone of a different generation increases the diversity of opinions you’re likely to experience. The music to which you listen may change. You may read different kinds of books, learn to laugh at different things. If you regularly inhabit another’s point of view, you are exercising very important regions of the brain. The quote “Sometimes you need to talk to a three-year-old so you can understand life again” is quite literally true. Plus, if the only friends you have are old, you will be attending many more funerals than weddings. And there’s nothing like watching the death of people around you to increase your sense of isolation. Having younger friends opens up a healthy can of life-goes-on, with a sparkling supply of weddings and baby showers in case you forget. Statistically, you’ve got a guarantee your young friends will outlive you.

Happily, the benefits of intergenerational friendship flow back into the life of the child. Regular interactions with older people increase a child’s problem-solving skills, positively influence emotional development, and improve language acquisition. Older people tend to be more patient, tend to look on the sunny side of life, and are more experienced with kids, often having raised children of their own. This ability to be kind, to listen, to empathize, is especially valuable for kids being raised in the chaos of a two-career family. Kids may always be the demander-in-chief, yet seniors who can make time for them and all their youthful foibles will discover the joys of being a wiser parent this time around.

So become someone’s favorite grandparent, as well as a mentor, friend, and confidant. Create peace in your marriage. Make friends with your neighbors. See your friends often.

And if you don’t?

All the lonely people

Researchers have uncovered three important facts about old age and loneliness. The first is as welcome as wrinkles: loneliness really increases with age. Depending on the study, the proportion of older adults experiencing at least moderate amounts of loneliness is anywhere between 20 percent and 40 percent. Second, loneliness throughout a person’s lifetime is uneven, following a U-shaped curve. Third, loneliness is the single greatest risk factor for clinical depression.

The definition of loneliness seems as obvious as drywall. You want to be around people and you can’t, so you feel bad. Defining loneliness in a scientifically specific way, though, is a bit tricky. Some people are “loners” and prefer life that way. Some folks favor pets over people. Others need humans around all the time. Researchers use the term “objective social isolation” for those who are isolated (and may even prefer it) and “perceived social isolation” for those who feel alone (and definitely do not prefer it). Here’s a laboratory definition for you: “A perceived lack of control over the quantity and especially the quality of one’s social activity.”

Scientists also have a psychometric test to measure what that quote means. Developed in one of the least lonely places on earth, Southern California, the test is appropriately called the UCLA Loneliness Scale. Here’s what researchers have found.

We start feeling lonely in late adolescence, and the feeling decreases as we move through early-to-middle adulthood. That’s natural: we go through school, jobs, kids—experiences chock-full of other people. Our number of friends rises sharply to peak at age twenty-five, then slowly drifts down to age forty-five, levels a bit, and continues its decline after fifty-five, completing the U shape of loneliness.

There are many caveats and nuances to these data, so the U curve’s a bit wobbly. Seventy-five-year-olds experience some of the least feelings of loneliness in life, followed by the most a month or two after their eightieth birthday. Seniors who don’t make much money experience severe loneliness more sharply than seniors who do: a monstrous threefold increase. Married people experience less loneliness than those living alone. This is true for all age groups, but the quality of intimacy plays a larger role for the marital well-being of seniors than of younger people. Physical health plays a powerful role in how much isolation the elderly suffer, too.

Where social isolation leads

The more socially isolated you become, the less happy you are. Researchers believe the reasons for this are deeply rooted in evolution: humans were too weak, biologically speaking, to survive without each other for long. Our brains created a system of negative responses to social isolation, compelling us to seek each other out. Cooperation and the mentalizing tools we developed for it put us squarely into the Darwinian carpool lane. We then survived long enough to pass along our genes.

We don’t do very well when we get lonely. For one, our social behaviors begin eroding. Loneliness is associated with poorer grooming habits, for example, and an increasing inability to navigate intimate life functions such as bathing, using the toilet, eating, dressing independently, and getting out of bed. Some of this may be related to the oncoming squalls of depression, gusts to which lonely seniors are particularly vulnerable.

Lonely seniors have poorer immune function. They can’t fight off viral infections or cancers as easily. They have higher levels of stress hormones, which bring on all kinds of negative effects. Chief among these are higher blood pressure, which increases the risk for heart disease and stroke. Loneliness hurts overall cognition too, from memory to perceptual speed. It’s even a risk factor for dementia.

Chronic loneliness can throw you into a nasty loop. As you probably know, the process of aging involves physical pain: certain tissues begin to break down for which there will be no cure; aches intensify in specific body parts naturally vulnerable to aging (arthritis is but one example). Such discomfort can affect your topics of conversation, your mobility, and your sleep. All combine to make you increasingly unpleasant to be around. The more unpleasant you are, the less people want to hang with you. Fewer social interactions make you more susceptible to the problems we’ve been discussing. You become even more unable to interact socially, and people quit visiting. This cycle repeats itself over and over again: the lonelier you are, the lonelier you become. And that’s when the attack dog of depression strikes. By the time people are in their eighties, loneliness is the single greatest risk factor for clinical depression. That’s a steaming bag of bad neural news, as we’ll discuss in a later chapter.

The most dramatic effect of social isolation on the elderly is death. The probability of death is 45 percent greater for lonely seniors than it is for socially active ones. That number holds steady even when you control for things like debilitating physical ailments and depression. If you don’t have a lot of friends, you die sooner than you have to.

Inflammation of the brain

“Tell us, Mrs. Holderness, what do you think is the best thing about being 103?” a journalist asked. Molly’s response was quick and good-humored: “No peer pressure.”

She is fortunate to have a sharp mind. Many elderly people don’t—and most of those are women. Neuroscientist Laura Fratiglioni wondered if there could be a connection between the fact that men die before women, leaving widows alone in life, and the fact that women suffer more dementia than men, especially after the age of eighty. Could isolation be the culprit? Fratiglioni determined there was indeed a correlation. Women who live alone, as well as those without strong social interactivity, are at much greater risk for dementia than those who live with someone or have sustained, close social interactions.

The brain mechanisms behind this disturbing finding were soon under active investigation. A clear, more causal picture has emerged: excessive loneliness causes brain damage.

This deserves a fuller explanation because it’s a really big thing to say. The biological machinery involves, of all things, the same mechanisms stimulated when you stub your toe.

You undoubtedly know about inflammation. You stub your toe and local infectious agents—like bacteria—sweep in to take advantage, launching their Lilliputian attacks. Your body responds with swelling, redness, profanity. The classic inflammatory response is supervised by many molecules, including ones called cytokines. The response usually doesn’t last very long; the cytokines do their job and, in a few days, destroy the unwanted bad actors. This is a case of acute inflammation.

There is another type of inflammation, however, related to stubbed toes and also involving cytokines, but more relevant to our story. It is called systemic or persistent inflammation, the key difference tucked into its name: it lasts a long time. This type of inflammation occurs all over the body. It’s akin to getting tiny toe-stubs throughout the major organ systems, then having your whole body react with systemic, low-intensity inflammation as a result.

Don’t let the phrase “low intensity” fool you. Systemic inflammation damages many types of tissue over a long period of time, the way acid rain eats into a forest. It can even damage the brain, particularly white matter. White matter is composed of myelin sheaths that wrap around neurons, providing insulation to improve electrical performance. Without it, the brain doesn’t function very well.

How do you get systemic inflammation? The paths are many, including environmental factors such as smoking, exposure to pollution, or being overweight. Stress, ever the acid reflux of behavior, can incite it. And so can loneliness, according to Timothy Verstynen, director of the Cognitive Axon Lab at Carnegie Mellon University. He found in 2015 that chronic social isolation increases the level of systemic inflammation. Just how much damage loneliness causes in humans turns out to be astonishing. It’s at the same level as smoking. Or being too fat. The proposed molecular mechanism for this extraordinary observation is like a three-step feedback loop from geriatric hell: (1) loneliness causes systemic inflammation, (2) the inflammation damages white matter in the brain, and (3) the damage leads to the changes in behavior we mentioned, the ones resulting in fewer social interactions. Repeat.

If there is that thin a membrane between loneliness and brain damage, we have some serious thinking to do about how society treats its seniors. And how seniors treat themselves. We need to spend some quality time being grateful for the friends we have, and if the friendship tank is low, we need to seriously strategize about how to refill it.

A cultural shift

Refilling your friendship tank can be tough to do as you age. Researchers know you increase the quantity of friends you have in life until about age twenty-five. Then the number begins a long, slow decline, a deterioration that won’t stop until late into middle age. Baby boomers are notorious for losing friends in later life. As seniors, they have fewer social interactions with people of nearly every stripe—family members, friends, next-door neighbors—than seniors did in the previous generation.

Sociologists concur there are multiple reasons for this decrease, though not every researcher agrees on exactly what they are. Some point to the fact that people of child-bearing age move around a lot. This means communities are constantly being formed, uprooted, and re-formed—not a condition conducive to creating rich, long-lasting adult friendships. As a result, the guarantee of relational stability that comes from staying in one place gets torn up. My grandparents celebrated the multi-decade wedding anniversaries of friends with whom they had also shared a first-grade classroom. Such a thing is almost beyond imagining today.

It doesn’t help that people in developed countries are having fewer children than a generation ago. Over time, this means fewer uncles, aunts, and cousins. Even though that also means fewer annoying family reunions to attend, it shrinks the probability of sustaining long-term relationships with relatives (even if you did stay in one place). So you don’t have close friends. You don’t have much family. You barely even have a home. In terms of breeding toxic isolation, that’s like stagnant water to a mosquito.

On top of that, the nature of friendship is changing. The digital world provides enticing electronic substitutes for flesh-and-blood interactions. An intense research effort is under way to see if this matters, and I’ll have more to say about it in a later chapter.

The bottom line: environmental forces put seniors at greater risk for being alone than ever before. That’s noxious, for at a time when your brain is already under corrosive assault from Darwinian-approved natural causes, social isolation is the last thing it needs.

And that’s not even the full story. Nature plays just as strong a role as nurture. It is to these ideas that we next turn.

Face time

Prosopagnosia. It’s tough to pronounce, tougher to experience. People who suffer from the P-word aren’t able to do something even infants can do: recognize faces. They may have known you for years, but they won’t recognize you if you walk into the room five minutes from now. Nor will they recognize anybody else, even though they usually can recognize every thing else. No problem with hats, for example, or with eyebrows, or even with the concept of “face.”

Sufferers of prosopagnosia (logically called face blindness) usually resort to extraordinary measures to navigate their social world. A person might have to memorize the clothes their family members regularly wear in order to tell them apart. Others might have to pay close attention to the way people move or to specific postures, in order to recognize people at work. The late neurologist Oliver Sacks, a famous sufferer of face blindness, would have his guests wear name tags at parties so he could recognize them.

Not surprisingly, many people with the disorder withdraw socially, often suffering from social anxiety. This makes a certain amount of sense, for a great deal of social information is carried by the face. Clues to whether someone is happy or sad, contented or disgusted, potential mate or potential threat, show up in the eyes, cheeks, and jowls. Without the knowledge of what someone is feeling, sufferers withdraw into a Twilight Zone world where people can recognize you but you can’t return the favor. Sacks himself quit attending conferences and large parties.

Prosopagnosia is associated with lesions in a brain region called the fusiform gyrus, an area in the lower part of your brain not far from where your spinal column enters your skull. Strokes and various head traumas can damage the fusiform gyrus. Face blindness also is as heritable as eye color, which means you can get it from your parents. It is thought to affect about 2 percent of the population. But a less severe form of it seems to be related to normal aging as well.

As people get older, they suffer an increasing inability to recognize familiar faces, and they lose their perception of some of the emotional information those faces carry. We even know the reason. The neural tracts—the white-matter cabling—connecting the fusiform gyrus to other regions of the brain begin to lose structural integrity. Prosopagnosia illustrates an important principle in the brain sciences: specific regions of the brain exert a dictatorship over specific functions. When those regions become injured, those functions can be altered—or disappear.

The behavioral deficits are not global. Seniors can recognize emotions like surprise, happiness, and even disgust just fine (in fact, they score better on tests measuring disgust than younger adults do). Not so with sadness, fear, and anger. It’s an unfortunate twofer: seniors have a harder time recognizing people they know, sort of like a mini-prosopagnosia, and they have a harder time recognizing certain feelings those people are experiencing.

Do seniors withdraw socially as a result of these deficits, similarly to people with face blindness? Though there is (always) the need for further research, the answer may be yes. As we discussed, people begin to withdraw from social interactions as they age (remember the peak at twenty-five and downward slope at fifty-five?). Seniors show an especially severe reduction. Interestingly, the same shrinkage in social activity occurs in lab-raised monkeys when they become elderly.

We’ve talked about mentalizing, or Theory of Mind. As you get older, the ability to mentalize begins to decline. In a lab assay called the “false belief task,” people try to guess the intention of someone else. Younger adults routinely get the correct answer about 95 percent of the time, elderly adults about 85 percent of the time. The senior scores worsen with age, such that after age eighty, the scores shrink to less than 70 percent. The reason appears to be an age-related change in the functional activity of a single region in the prefrontal cortex. The prefrontal cortex (often abbreviated as PFC) is evolution’s newest add-on to your brain’s fundamental architecture. It’s a most talented structure, with functions ranging from decision making to personality formation. As we’ll discover later, most of the talents we identify as uniquely human arise in the PFC.

Is it possible that changes in facial recognition and changes in mentalizing ability are related? And if so, might they be part of nature’s contribution to the social isolation experienced by many of our elderly? The real answer is we don’t know. But the fact that I can write about this stuff in a scientifically meaningful fashion at all represents a tremendous leap in our understanding from even a few years ago. Such progress has even bled into the practical realm of intervention. Solid research shows steps we can take to ameliorate the negative effects of loneliness. It is to these steps that we turn next.

Dance the night away

The years of age separating dancers Mikhail Baryshnikov and Fred Astaire span about a half century. No matter: the Latvian’s admiration for his American colleague is evident. “No dancer can watch Fred Astaire and not know that we all should have been in another business,” said the legendary Soviet and American ballet dancer. He was describing the Hollywood movie star and legendary hoofer, who danced with just about every leading lady in twentieth-century American film, and also with brooms, rotating rooms, firecrackers, even his own shadow. He inspired a whole generation of Americans to get out there and dance the night away, with a chain of franchisable dance studios trumpeting the cause. As a brain scientist, watching his seemingly effortless movements, I say he should inspire us again. Unfortunately, he died in 1987, at the ripe old age of eighty-eight.

The reason for my enthusiasm is scientific. You can cover the dance floor with peer-reviewed papers showing the benefits of this regular, ritualized movement that forces social interaction. The scientific benefits are almost too good to be true.

Consider one study, where researchers enrolled healthy older adults, ages sixty to ninety-four, in a six-month dance class, one hour per week. The investigators assessed a broad range of cognitive and motor skills before class commenced, then assessed them again six months later. Non-dancing controls were also measured.

The results were as welcome as free tickets to the Bolshoi. Hand-motor coordination (as measured by a standardized Reaction Time Analysis assay) improved by about 8 percent in six months. That might not sound like much, until you consider that the scores of the controls actually decreased during the same period. Suites of cognitive skills were tested, including fluid intelligence, short-term memory, and impulse control. These increased by an impressive 13 percent during the dance class. Posture and balance (measured by using the so-called forced-platform test) increased by about 25 percent in the dancers over their previous scores. And again, the nondancers showed a net decrease. Half a year later, the dancers did not move the same way—or think the same way.

The type of dance didn’t seem to matter. Tango, jazz, salsa, folk, various kinds of ballroom dancing: all exerted their whirling wizardry on the brain. Further research has shown that other forms of ritualized movement instruction, such as tai chi and various martial arts, also show benefits in many of these same measures.

One of the most unexpected findings had to do with the number of falls experienced by seniors who took movement classes. During the testing period in one tai chi program, the number of falls fell by 37 percent. Falling is not a trivial issue for the elderly, and for the two reasons they care the most about: head injuries and bank accounts. In the United States, medical expenses from seniors’ falls total more than $30 billion a year. In Australia, fall-related injuries among the elderly take nearly 5 percent of the health care budget.

Fred Astaire was obviously on to something.

The human touch

Why does dancing work? The truth is we’re not sure. Undoubtedly exercise plays a part. Dancing requires participants not only to learn and memorize synchronized coordinated movements but also to muster up the energy to perform them. There are socialization arguments to consider, too. In most of these studies, a room full of people would be dancing, often as partners, requiring at least a two-drink minimum equivalent of social interactivity.

Finally, there is the idea of face-to-face interactions. And here we have something of a surprise. Depending on the style, dancing allows the opportunity for a certain amount of human touch. That’s important for anybody, but it’s wildly important for the elderly. The benefits of touch for senior brains—and just about everybody else’s brains—have been studied in the laboratories of such notable scientists as Dr. Tiffany Field, director of the Touch Research Institute at the University of Miami. She didn’t study dancing. She studied massage, and was among the first to show powerful cognitive and emotional boosts associated with the practice.

Virtually everybody Field has ever tested has shown the benefits of touch, from our oldest citizens in nursing homes to our youngest premature citizens in NICUs (neonatal intensive care units).

Field didn’t have to hire a formal masseuse to get the benefit. Even infrequent touching by nonprofessionals, like your friends, helps cement relationships (if the touch is welcome, not exploitive). Fifteen minutes a day will do. That may help explain the invisible devilry of the dance floor, for you often get and give much more than fifteen minutes of touch.

This leads to some practical advice. If you are a younger person, learn how to dance, then keep up the activity clear into your retirement years. If you are already old enough to think about retirement, this recommendation is even stronger. If you already know how to dance, find a place where you can cut a rug regularly. And if you don’t know how to dance, take a class, then start your rug cutting.

This helps us settle a digital question, too. As you know, I think social media is a country for old men and women, especially poignant for the mobility impaired. Yet the preferential power of face-to-face communication is clear. Whenever there is a choice to have it, choose it. When at all possible, allow other humans to share the same oxygen as you. Yes, such contact has its pitfalls, but it is what the brain needs in its twilight years. You may feel awkward on a dance floor. You may feel awkward talking instead of typing. Yet for the millions of years we have evolved, we had flesh-and-blood interactions, not server-and-CPU interactions.

Considering the power of socialization on the brain, being with each other is the most natural thing in the world.

SUMMARY

Be a friend to others, and let others be a friend to you

• Keep social groups vibrant and healthy; this actually boosts your cognitive abilities as you age.

• Stress-reducing, high-quality relationships, such as a good marriage, are particularly helpful for longevity.

• Cultivate relationships with younger generations. They help reduce stress, anxiety, and depression.

• Loneliness is the greatest risk factor for depression for the elderly. Excessive loneliness can cause brain damage.

• Dance, dance, dance. Benefits include exercise, social interactivity, and an increase in cognitive abilities.