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introduction

I PRESENT IN THE pages of this book everything you need to know about why you are aging. And I am going to use brain science to show how you can make life a surprisingly fulfilling experience—at least for your brain—in the years you have left. We begin with a group of seventy-year-old men in the capable hands of famed Harvard researcher Ellen Langer.

Lively—almost childlike—the seventy-year-old men skipped out of a monastery one fine morning. They’d just spent five days living in the old building, under observation by Langer. Now the men were leaving for home—smiling, happy, active, laughing. It was the fall of 1981, the first year of Ronald Reagan’s administration, and the men had the same sunny abandonment associated with our fortieth president—who, coincidentally, was exactly their age. But these seniors, as part of Langer’s research project, had just been through a time warp. Their brains had spent the past workweek not in 1981, but in 1959. The monastery was filled with songs like “Mack the Knife” and “The Battle of New Orleans.” On the black-and-white TV, the Boston Celtics beat the Minneapolis Lakers in the finals (yes, Minneapolis Lakers) and Johnny Unitas played for the Baltimore Colts. Issues of Life magazine and the Saturday Evening Post lay about. Ruth Handler had persuaded Mattel to create a thin, full-figured doll named after Ruth’s daughter, Barbie, and then market it to little girls who had yet to undergo puberty. President Eisenhower had just signed into law the Hawaii Admission Act, creating the fiftieth state.

That walk down memory lane was the reason the men were so happy as they left the monastery. Waiting for the bus to take them home, a few entered into a spontaneous game of touch football—an activity most had not done for decades.

You might not have recognized these men 120 hours previously. They were shuffling, with poor vision, hearing, and memory; some of the men required canes to walk into the monastery. A few could not carry their suitcases up to their rooms. Langer and her team had poked and prodded the men’s bodies and assessed their brains. These baseline tests proved one thing: before entering the monastery, the men were stereotypically old, as if ordered from Central Casting under the request “Eight infirm seniors, please.”

But they didn’t stay infirm. At the end of their stay, they underwent the same tests. Reading about the quantifiable change took my breath away. Even a casual visual inspection of these seniors revealed that something dramatic had happened, as the New York Times reported. Their posture was more robust. Their hands gripped more tightly. They handled objects with greater dexterity. They moved more easily (touch football, for heaven’s sake!). Their hearing had sharpened. Same with their vision. Yes, vision. A sampling of their conversation would have told you something in their brains had dramatically improved too, and this impression would be proved by a second round of IQ and memory tests. In honor of its extraordinary finding, the experiment has been christened the “counterclockwise study.”

The book you have in your hands is all about what happened to the men during those five days. And what will happen to you, statistically speaking, if you follow the advice in these pages. Such optimism is rare for me. I’m a grumpy neuroscientist. That means every scientific sentence in this book describes something published in the peer-reviewed literature, often replicated many times. (See www.brainrules.net/references.) I specialize in the genetics of psychiatric disorders. But if you think aging is all about debilitation, you may want to spend some quality time with another point of view, like Langer’s. Or the one in this book.

Brain Rules for Aging Well describes not only how the brain ages but also how you can reduce the corrosive effects of aging. This field of inquiry is called geroscience.

As you peruse these pages, you’ll discover what geroscientists already know. You’ll learn how to improve your memory, why you should hang on to your friends for dear life—literally—and why you should go dancing with them as often as possible. You’ll discover why reading a book several hours a day can actually add years to your life. You’ll find that learning a new language may be the best thing for your mind, especially if you’re worried about dementia. And that regularly engaging in friendly arguments with people who disagree with you is like taking a daily brain vitamin. You’ll also learn why certain video games can actually improve your ability to solve problems.

Along the way, we’ll dispel a few myths. Forget the double-your-order-if-you-call-now Elixir of the Fountain of Youth—there is no such thing. When it comes to causes of aging, wear and tear is less detrimental than a failure to repair. And it is not inevitable that your mind will power down as the years pass. If you follow the advice in this book, your brain can remain plastic, ready to study, ready to explore, and ready to learn at any age.

We’ll also discover there are benefits to aging, with dividends paid not just to your head but to your heart. Your ability to notice the glass is half-full actually increases the older you get, and stress levels decline. That’s why you should never listen to anyone who tells you old age is automatically filled with grumpy people. If you do it right, old age can be some of the happiest years of your life.

Four sections

Brain Rules for Aging Well is organized into four sections. First up, the social, or feeling, brain, exploring topics such as relationships, happiness, and gullibility to illustrate how our emotions change with age. Next, the thinking brain, explaining how various cognitive gadgets change with time. (“Gadgets” is my way of describing complex, interconnected brain regions with multiple functions.) Some actually improve, by the way. The third section is all about your body: how certain kinds of exercise, diets, and sleep can slow the decline of aging.

Each of these chapters is sprinkled with practical advice, explaining not only how certain interventions can improve performance but also what is known about the brain science behind each intervention.

The final section is about the future. Your future. It’s filled with topics as joyful as retirement and as inevitable as death. I’ll connect the previous chapters into a plan for maintaining your brain health. And you’ll want to pay attention to all of them. The reason for this is nicely explained by the Amazon River. Or, rather, nicely explained by Sir David Attenborough’s insights into the Amazon River.

A mighty river

As a youngster, I would watch the extraordinary TV documentaries narrated by this famed naturalist, and he disabused me of more errors about the natural world than I care to admit. One error had to do with the Amazon River.

I used to think the origin of the world’s thickest river was a single burbling spring that somehow magically swelled in size as it flowed across the land. You know, like most rivers. I felt dismay when Attenborough pronounced that the Amazon had no such singularity. Like most rivers. Wading through a tiny stream in his Living Planet series, he intoned: “This is one of the many streams that can claim to be a source of the biggest river on earth—the Amazon!” And later: “The many sources of the Amazon began as numberless rivulets on the eastern flanks of the Andes.” How disappointing! There was no single-origin story for 20 percent of the world’s freshwater. There were many smaller sources, each making an e pluribus unum contribution to a final, massive outflow.

It’s a pattern we’ll encounter again and again. Take the memory chapter. Science shows that many factors contribute to keeping your massive memory streams flowing strong. Staying stress-free plays a role. So do regular aerobic exercise and how many books you read last week and how much pain you are currently experiencing and whether you get a good night’s sleep. These factors serve as rivulets, each making a contribution to the larger Amazonian ability to recall things.

We now know that keeping the brain working well into old age involves creating lifestyles that act like streams high in the Andes. To best understand how we can retain our own intellectual effervescence, this book will wade into the contributions of each stream.

Toward the end of our discussion, I’ll describe how scientists are trying to hack into the molecular machinery of the aging process itself, tinkering with its “inevitability code” in an attempt to reverse the irreversible. As an AARP-eligible father, I embrace this effort wholeheartedly, though as an AARP-eligible scientist, I temper my enthusiasm with a healthy dose of scientific grumpiness.

It will then be time to revisit Langer’s lively septuagenarians, for the results of her time-warp studies will now make more sense. I won’t be sugarcoating the harsh ways in which time can run roughshod over the human experience. But you will come away understanding that there is a lot more to aging than aches and pains and longing to return to the days of the Eisenhower administration.

It’s a good time to grow old

We’ve got it relatively good. For virtually our species’ entire history, human life expectancy was about thirty years. Life expectancy is the benchmark for what’s typical. And it has been steadily rising. Were you living in England in 1850, you generally died in your mid-forties. That figure is four decades longer now. If you were an American in 1900, you died around age forty-nine. It was seventy-six by 1997.

Not true anymore. Americans born in 2015 can expect to live to seventy-eight (it’s a little more for women, a little less for men). If you’ve already made it to your sixty-fifth birthday, you can expect to live nearly twenty-four more years if female and nearly twenty-two more years if male. That’s an astonishing 10 percent jump since the year 2000, and the numbers are expected to go even higher.

If life expectancy gives us a benchmark for what’s typical, what’s possible?

When we look at the years a creature is capable of living, we’re talking about longevity (more properly, longevity determination). This number is regulated, somewhat indirectly, by genes. If you used the term “genetic longevity determination,” researchers in the room would nod their heads in approval.

This notion is different from maximum life span, and both are different from life expectancy. It’s easy to conflate them, which would earn you a frown from those researchers. The scientific journal Nature published succinct definitions a few years back: “Maximum life span is a bald measure of years accumulated. It is not the same as life expectancy, which is an actuarial measure of how long one is expected to live from birth, or indeed from any given age.”

In this view, longevity is the amount of time you could spend on the planet were conditions ideal. Life expectancy is the amount of time you likely will spend on the planet, given that conditions are almost never ideal. It’s the difference between how long you can live versus how long you will live.

So how long can humans live? The oldest person with an independently verifiable birth date celebrated her 122nd party before passing. But most of the oldest people clock in between 115 and 120 years old. You’d have to weather a lot of biological perfect storms to get to your 120th birthday party, of course, and almost none of us will. The probability isn’t zero, though.

We really are learning how to soldier on right to the edge of our expiration dates. And, as the stories throughout this book illustrate, we’re doing it in greater physical and mental health than at any other time in our history.

But these stories can’t tell you how you will age. That’s because aging is quite variable—even individually expressed. There’s an intricate fox-trot between nature and nurture. And the fact that the brain is so flexible, so damnably reactive to its environment, is actually a powerful confounder for many types of brain research. The brain appears hardwired not to be hardwired. Consider the simple act of reading this sentence and discovering I’ve left the period off the end of it The very fact that I did, and that I told you, and that you probably looked to see if I was telling the truth, physically rewired your brain.

How the brain is wired

Whenever the brain learns something, connections between neurons change. What does that look like? Neural circuitry has many options. Sometimes the changes involve neurons growing new connections to the locals. Sometimes the changes involve abandoning certain connections and re-forming new ones somewhere else. Sometimes the alterations only involve electrical relationships between two neurons, something called synaptic strength.

You probably learned in high school that brains are strung together with electrically active nerve cells—neurons—but you may have forgotten what they looked like. To illustrate, I’d like to introduce you to what are easily the First Ladies of my wife’s garden, our two graceful Japanese maples. They’re beautiful creatures, more bush than tree, with elegant, tapered leaves, deeply red in the autumn. These leaves are fastened to complex branches, which gather at a stubby trunk. The trunk is nearly hidden from view, given the exuberance of the branching, and the little you can see quickly dives under the soil. The underground part of the maple splits into a slightly less complex root system, like most plants.

Though neurons come in many shapes and sizes, all follow a basic structure, looking something like our garden’s Grand Dames. Impossibly complex branching structures, called dendrites, exist at one end of a typical cell. Those dendrites gather together into a trunk-like structure termed an axon. Unlike our maple’s trunk, however, there is a bulge at this point of gathering. It’s an important swelling—called the cell body—and its reputation derives from a small spherical shape inside it. This is the nucleus of the neuron. It houses the cell’s command and control structures, the double-ladder-shaped molecule DNA.

Axons can be short and squatty, like our maple’s trunk, or long and slender like a pine tree’s trunk. Many are wrapped in a type of “bark” that’s called white matter. At the other end of the axon lies a root system, just like a plant’s, consisting of branching structures termed telodendria. These usually aren’t as complex as the dendrites, but they serve an important information-transfer function, as we’re about to see.

The brain’s information system runs on electricity, like most light bulbs, and their shape helps them do it. To understand how, imagine pulling one of our Japanese maples out by its roots, and then, while my wife has a heart attack, holding it over the top of our other maple. Don’t let them touch. The root system of the top tree is now hovering over the branches of the bottom.

Now imagine these two trees are neurons. The telodendria (roots) of the upper neuron lie close to the dendrites (branches) of the lower cell. In the real world of the brain, electricity flows from the dendrites of the top neuron down its axon and arriving at the telodendria, where it immediately encounters the space between the two. The gap must be jumped if information is to be transferred. This junction is called a synapse, and the space it creates, the synaptic cleft. How to pole-vault the space?

The solution lies at the tips of those root-like telodendria. There are small bead-like packets at those tips containing some of the most famous molecules in all of neuroscience. They’re called neurotransmitters. I’ll bet you’ve heard of some of them: dopamine, glutamate, serotonin.

When an electrical signal reaches the telodendria of one neuron, some of these biochemical celebrities are released into the synaptic cleft. It’s the equivalent of saying, “I need to send a message to the other side.” The neurotransmitters dutifully sail across the gulf. It’s not a long journey; most of these spaces are only about 20 nanometers in length. Once the neurotransmitters have crossed, they bind to receptors on the dendrites of the other neuron, like a boat tying up to a dock. This binding is sensed by the cell, alerting it with signal that says: “Oh, I better do something.” In many cases, that “do something” means becoming electrically excited too. It then passes along this excitement down the chain from dendrites to axons to its telodendria.

While jumping the space between two neurons using biochemicals is a neat trick, the electrical circuits aren’t usually this simple. If you can imagine lining up thousands of cellular Japanese maples root-to-branch, you’d have something approximating an elementary neural circuit in the brain. And even that’s too simple. The typical number of connections a single neuron makes with other neurons is around seven thousand. (That’s only an average: some have more than a hundred thousand!) Under the microscope, neural tissue looks like thousands of maple trees have crashed together in one space, whipped by an F5 tornado.

These are the structures that change so flexibly when the brain learns something new. These are the structures that become damaged as we age. However, there’s another fascinating reason that the damage of aging is incredibly individual.

The brain doesn’t just react to changes in the outside environment. Remarkably, the brain can respond to changes it observes happening to itself. How does it do that? We’ve no idea. We do know that if it senses the changes are likely to be negative, it can create work-arounds to fix the problem.

Cells erode, lose connections, or simply stop functioning. These alterations could easily lead to behavioral changes, but they don’t always. The reason is that the brain kicks into compensatory overdrive and reroutes itself according to a new plan.

The major culprit in aging is a hot topic. Some scientists speculate about immune system deficiency (the immunologic theory). Others blame dysfunctional energy systems (the free radical hypothesis; mitochondrial theory). Others point to systemic inflammation. Who is correct? The answer is all of them. Or none of them. Each hypothesis has been found to explain only certain aspects of aging. The sum total is that many systems get hit as we grow old, but which ones sign off first is individually experienced.

There are nearly as many ways to transit through the aging process as there are people on the planet. It’s a theme as familiar as shopping for jeans: one size does not fit all. Discernible generalizable patterns do exist, and studying the brain is a great way to see some of them. But to get an accurate view, we’re going to have to gaze at an occasionally cloudy statistical mirror. It’s okay. We’ll still look fabulous. We’ll just be a little older.

Our goal is to learn how to create lifestyles that will continually grease the biological gears controlling how long we live. And how well we live. Fortunately for us, geroscience is well funded. Scientists have discovered many cool things we can do as our brains age. All of these discoveries over the years add up to one thing: science is literally changing our minds about the optimal care and feeding of the brain. All of it is captivating. A great deal of it is unexpected. One of the most delightful is the subject of our first chapter. It’s the jovial power of having lots of friends.

SUMMARY

• Geroscience is the field of inquiry dedicated to studying how we age, what causes us to age, and how we can reduce the corrosive effects of aging.

• Aging is mostly due to the breakdown of our biological maintenance departments, our body’s increasing inability to repair the day-to-day wear and tear adequately.

• Today, we humans are living much longer than we have for the majority of our existence. We are the only species capable of living past our prime.

• The human brain is so adaptable that it reacts to changes not only in its environment but also within itself. Your aging brain is capable of compensating for breakdowns in its own systems as you get older.