Keep Sharp

Build a Better Brain at Any Age

Sanjay Gupta

• Publisher: Simon & Schuster
• Year: 2021
• ISBN:
  9781501166754
• Topic: Psychologie
• Subtopic: Neurosciences cognitives et neuropsychologie

Keep your brain young, healthy, and sharp with this science-driven guide to protecting your mind from decline by neurosurgeon and CNN chief medical correspondent Dr. Sanjay Gupta. Throughout our life, we look for ways to keep our minds sharp and effortlessly productive. Now, globetrotting neurosurgeon Dr. Sanjay Gupta offers "the book all of us need, young and old" (Walter Isaacson, #1 New York Times bestselling author of The Code Breaker ) with insights from top scientists all over the world, whose cutting-edge research can help you heighten and protect brain function and maintain cognitive health at any age. Keep Sharp debunks common myths about aging and mental decline, explores whether there's a "best" diet or exercise regimen for the brain, and explains whether it's healthier to play video games that test memory and processing speed, or to engage in more social interaction. Discover what we can learn from "super-brained" people who are in their eighties and nineties with no signs of slowing down—and whether there are truly any benefits to drugs, supplements, and vitamins. Dr. Gupta also addresses brain disease, particularly Alzheimer's, answers all your questions about the signs and symptoms, and shows how to ward against it and stay healthy while caring for a partner in cognitive decline. He likewise provides you with a personalized twelve-week program featuring practical strategies to strengthen your brain every day. Keep Sharp is the "must-read owner's manual" (Arianna Huffington) you'll need to keep your brain young and healthy regardless of your age!

PART 1

CHAPTER 1 What Makes You You

Imagine the brain, that shiny mound of being, that mouse-gray parliament of cells, that dream factory, that petit tyrant inside a ball of bone, that huddle of neurons calling all the plays, that little everywhere, that fickle pleasure dome, that wrinkled wardrobe of selves stuffed into the skull like too many clothes into a gym bag.

DIANE ACKERMAN (FROM AN ALCHEMY OF MIND)

It was 1992 when I first saw a living human brain, a powerful and life-changing experience for me. It was, and still is, hard for me to believe that so much of what we are, who we will become, and how we interpret the world resides in that intricately woven bundle of tissue. When I am describing a neurosurgery procedure, most people try to visualize what the human brain looks like, and they typically are a little off base. For starters, it doesn’t look like a dull and bland gray mass on the outside, despite being referred to as gray matter. It is more pinkish with whitish yellow patches and large blood vessels coursing on and through it. It has deep crevasses, known as sulci, and mountainous peaks, known as gyri. Deep fissures separate the brain into the various lobes in a surprisingly consistent way. During an operation, the brain pulsates gently out of the skull’s borders and looks very much alive. Consistency wise, it is not so much rubbery as squishy, more like gelatin. It has always amazed me how fragile the brain is despite its incredible function and versatility. Once you see the brain, you very much want to protect it and take care of it.

To me, the brain has always been a bit mystical. Weighing in at a little over three pounds, it comprises all the circuitry we need to do just about everything. Think about that for a moment: It weighs less than most laptop computers, yet it can perform in a way that no computer can or will ever rival. In fact, the oft-cited metaphor of brains being like computers fails in oh-so-many ways. We may speak in terms of the brain’s processing speed, its storage capacity, its circuitry, and its encodings and encryptions. But the brain doesn’t have a fixed memory capacity that is waiting to be filled up, and it doesn’t calculate in the manner a computer does. Even how we each see and perceive the world is an active interpretation and result of what we pay attention to and anticipate—not a passive receiving of inputs. It is true that our eyes see the world upside down. The brain then takes the input and converts it into a coherent image. In addition, the back of the eye, the retina, provides the brain with two-dimensional images from each eye, which the brain then converts into beautiful, textured three-dimensional images, providing depth perception. And we all have blind spots in our vision that our brain constantly fills in using constant data you probably didn’t even realize you were collecting. No matter how sophisticated artificial intelligence becomes, there will always be some things the human brain can do that no computer can.

Compared to other mammals, our brain’s size relative to the rest of our body is astonishingly large. Consider the brain of an elephant: It takes up 1/550 of the animal’s total weight. Our brain, on the other hand, is about 1/40 of our body weight. But the feature that most sets us apart from all other species is our amazing ability to think in ways that reach far beyond mere survival. Fish, amphibians, reptiles, and birds, for instance, are assumed not to do much “thinking,” at least in the way we conceive of it. But all animals concern themselves with the everyday business of eating, sleeping, reproducing, and surviving—automatic instinctual processes under the control of what’s called the “reptilian brain.” We have our own inner primitive reptilian brain that performs the same functions for us, and in fact it drives much of our behavior (perhaps more than we’d like to admit). It is the complexity and large size of our outer cerebral cortex that allows us to perform more sophisticated tasks than, say, cats and dogs. We can more successfully use language, acquire complex skills, create tools, and live in social groups thanks to that bark-like layer of our brain. Cortex means bark in Latin, and in this case, it is the outer layer of the brain, full of folds, ridges, and valleys. Because the brain folds back on itself over and over again, its surface area is far larger than you might guess—a little over two square feet on average, though exact calculations do vary (e.g., it would spread out over a page or two of a standard newspaper).¹ And probably somewhere deep in those crevasses is likely the seat of consciousness. Heady stuff!

The human brain contains an estimated (give or take) 100 billion brain cells, or neurons, and billions of nerve fibers (although nobody knows these numbers exactly for sure—because exact calculations are impossible as of yet).² These neurons are linked by trillions of connections called synapses. It is through these connections that we are able to think abstractly, feel angry or hungry, remember, rationalize, make decisions, be creative, form language, reminisce about the past, plan the future, hold moral convictions, communicate our intentions, contemplate complex stories, pass judgment, respond to nuanced social cues, coordinate dance moves, know which way is up or down, solve complex problems, tell a lie or a joke, walk on our tiptoes, notice a scent in the air, breathe, sense fear or danger, engage in passive-aggressive behavior, learn to build spaceships, sleep well at night and dream, express and experience deeply felt emotions such as love, analyze information and stimuli in an exceptionally sophisticated fashion, and so on. We can do many of these tasks at the same time, too. Perhaps you’re reading this book, drinking a beverage, digesting your lunch, plotting when you’ll get to your cluttered garage this year, thinking about your weekend plans (“in the back of your mind”), and breathing, among many other things.

Each part of the brain serves a special, defined purpose, and these parts link together to function in a coordinated manner. That last part is key to our new understanding of the brain. When I was in middle school, the brain was thought to be segmented by purpose—one area was for abstract thought, another for coloring within the lines, yet another for forming language. If you took high school biology, you may have heard the story of Phineas Gage, one of the most famous survivors of a serious brain injury. You may not know, however, just how much his unfortunate accident illuminated for scientists the inner workings of the brain at a time long before we had advanced techniques to measure, test, and examine brain functions. In 1848, the twenty-five-year-old Gage was working on the construction of a railroad in Cavendish, Vermont. One day, as he was packing explosive powder into a hole using a large iron rod measuring 43 inches long and 1¼ inches in diameter and weighing 13¼ pounds, the powder detonated. The rod shot upward into his face, penetrating Gage’s left cheek. It traveled all the way through his head (and brain) and out the top. His left eye was blinded, but he didn’t die and possibly didn’t even lose consciousness or experience severe pain, telling the doctor who first attended to him, “Here is business enough for you.” On the next page is a photo (known as a daguerreotype in early photographic technology) taken of Gage after recovering from the accident as he holds the offending tamping iron. This photo was only recently discovered and identified in 2009. To the right is a drawing made by Dr. John Harlow who treated him and recorded this sketch in his notes that became a publication of the Massachusetts Medical Society.³

Gage’s personality, however, did not survive the blow intact. According to some accounts, he went from being a model gentleman to a mean, violent, unreliable person. The curious case of Phineas Gage was the first to demonstrate a link between trauma to certain regions of the brain and personality change. It had never been that clear-cut before. Keep in mind that in the 1800s, phrenologists still believed that measuring the size of bumps on a person’s skull could be used to assess personality. Twelve years after the accident, Phineas Gage died at age thirty-six after experiencing a series of seizures. He has been written about in the medical literature ever since, becoming one of neuroscience’s most famous patients. There was something else Phineas Gage taught us that is particularly important for this book. Some accounts of his life document a return of his more amiable nature closer to his death, which indicated the ability of the brain to heal and rehabilitate itself, even after significant trauma. This process of reestablishing networks and connections in areas of the brain damaged by the injury is what’s called neuroplasticity, an important concept we’ll be exploring. The brain is a lot less static than we thought in the past. It’s alive, growing, learning, and changing—all throughout our lives. This dynamism offers hope for everyone looking to keep their mental faculties intact.

Photo of Phineas Gage and line drawing made by the town doctor, John M. Harlow, who helped treat him.

Although documentation on Gage’s accident gave us a glimpse of the brain’s complexity and the connection to behavior, it still took more than another century for us to understand that the brain’s stunning power isn’t simply due to its individual anatomical compartments. It’s the circuitry and communication between those sections that make up our complicated responses and behaviors. Many areas of the brain develop at different paces and in different stages of our life. For this reason, an adult solves problems differently and faster than a child does, an older person might struggle with motor skills such as walking and coordination in the dark, and the teenager might be a track-and-field star with perfect vision.

When most of us think about the brain, we probably think about the element of it that makes us, well, us. We ponder the mind—the part that includes our consciousness and is reflected by that quintessential inner voice or, as some would say, that monologic chatter we listen to all day long. It is your you that bosses you around all day, raises important as well as inane questions, beats you up emotionally on occasion, and makes life a series of decisions. I also have been mystified that every moment of jealousy, insecurity, and fear we have ever experienced lies within the caverns of the brain. And somehow the brain can take in data and create hope, joy, and pleasure.

The mind is what first drove me to study the brain. Oddly, however, we still don’t really know precisely where consciousness resides in the brain or if it is even in the brain entirely. I find this to be a fundamentally important point. That state of being aware of oneself and one’s surroundings—consciousness—on which everything else is predicated, remains elusive. Sure, I can tell you where in your brain rests the networks for processing sight, solving a math equation, knowing how to speak a language, walking, tying your shoelaces, and planning a vacation. But I cannot tell you exactly where your self-awareness comes from; it is probably the result of a confluence of factors throughout the brain—the outcome of metacognition, activities that involve multiple regions of the brain in their interconnectivity.

Getting to the brain is a highly orchestrated and meticulously planned journey. First, the skin is cut. Incidentally, it is the skin that contains pain fibers that must be dulled to perform brain surgery; the skull and the brain itself, that organ that innervates the entire body, has no sensory receptors of its own. It is why conducting brain surgery on an awake patient is an option (and probably why Phineas Gage felt little pain). The dura mater (“tough mother”)—the layer covering the brain—has a few sensory fibers as well, but the brain itself does not. It is “so meta,” as the kids say.

Once I’ve gotten inside someone’s head (literally), I usually have a moment when I reflect on the fact that the brain can now be manipulated way too easily. After you have snuck into the castle (the skull), you have free rein. The brain floats in a bath of clear fluid and has no discernible smell. The brain offers nearly no resistance as you dissect, prod, probe, and cut. A patient could lose function of a limb if too much pressure is placed in one area or develop crippling dizziness from pressure in another section. A single snip could rob the patient’s sense of smell, and a bigger snip could be blinding or worse. I’ve often wondered why the brain wouldn’t put up more of a fight.

Knowing how vulnerable a brain can be on its exposure during surgery, I feel like a SWAT team member whenever I operate on one, or maybe I’m more like a highly trained thief. My goal is to get in, take what I need—say, a tumor, abscess, or aneurysm—and get the hell out without ever being detected. I want to disrupt the brain as little as possible.

Perhaps because it is encased in solid bone, the brain is often treated as a black box, viewed only in terms of its inputs and outputs without full knowledge of its internal workings. Impenetrable and indecipherable. And perhaps that is why the medical establishment simply resorted to the convenient adage that “what is good for the heart is also good for the brain.” Truth is, though, that the saying became popular largely because both the heart and the brain have blood vessels. The brain, of course, is exponentially more intricate. What’s more, the heart is a glorified pump, an engineering marvel for sure, but still a pump that can now be replicated in an engineer’s laboratory. There is no true metaphor for the brain. If you become brain dead due to some horrible head injury, there is no replacement. It is the command central for not just our body but for our existence. Despite how much we have mapped it, probed it, infused it with chemicals, we are still not exactly sure what makes it tick or slows its tick. This has no doubt played into our frustrations in understanding and treating neurodegenerative decline and complex disease processes and disorders of the brain, from autism to Alzheimer’s.

Now here’s the silver lining: We may never know all the mysterious perplexities of the human brain and come to control it like my parents can an automobile, and that is okay. Maybe we are not supposed to know where consciousness resides or how our personal perceptions and perspectives are neuronally born. No, we can’t touch our brains the way we can our skin or nose, but we know it’s there, just like the air we breathe and the wind we feel on our face. We also know it’s home to another bewildering marvel we cannot see, touch, or feel but immediately associate with the brain: memory—the process of remembering—but it’s much more than that, as you are about to learn. It is what makes us uniquely human, and it’s the first pillar of having a sharp, fast-thinking, resilient brain.

Brainy Facts

1. The typical human brain comprises about 2 to 2.5 percent of the body’s total weight but uses 20 percent of its total energy and oxygen intake.
2. Your brain is roughly 73 percent water (same for your heart), and that is why it takes only 2 percent dehydration to affect your attention, memory and other cognitive skills, so drinking just a few ounces of water can reverse that.
3. Your brain weighs a little over three pounds. Sixty percent of the dry weight is fat, making the brain the fattiest organ in the body.
4. All brain cells are not alike. There are many different types of neurons in the brain, each serving an important function.
5. The brain is the last organ to mature. As any parent can attest, children’s and teenagers’ brains are not fully formed, which is why they take to risky behaviors and can have a harder time regulating their emotions. It isn’t until about the age of twenty-five that the human brain reaches full maturity.
6. Brain information can travel faster than some race cars, up to more than 250 miles per hour.
7. Your brain generates enough electricity to power a low-wattage LED light.
8. The average brain is believed to generate tens of thousands of thoughts per day, give or take.
9. Every minute, 750 to 1,000 milliliters of blood flow through the brain. This is enough to fill a wine bottle and then some. Every minute!
10. Your brain can process a visual image in less time than it takes for you to blink.
11. The hippocampus, the part of the brain considered the memory center, has been documented to be significantly larger in people whose jobs have high cognitive demands, compared to the average person. London cab drivers, for instance, get a mental workout while navigating London’s 25,000 streets. However, those memory cen...