What appealed to Davidson about studying the middle-aged was that they have had their share of life experiences. Their resilience has been tested. They have had the opportunity to learn how to better cope with adversity, and their reactions, repeated thousands of times over the years—to a delayed train, a child’s accident, an overdue bill, a lost wallet, a split pair of pants—have etched themselves in the body. It is the perfect time to observe the diverse patterns of emotional reactions that people develop.
Davidson believes that coping effectively with adversity is at least one element of staying healthy. Chronic stress has been linked to cancer, type 2 diabetes, and cardiovascular disease. Recent experiments have demonstrated that just the perception of intense stress can make the body’s cells age more rapidly—perhaps as much as ten years—by eating away the tips of each cell’s chromosomes. The pressing question is whether people can learn to control their emotions and anxieties. Such composure is particularly important for people in their middle decades, when the stresses of family, work, and finances are at their peak and the physical wear that plays out in later years first surfaces.
MIDUS II offered an unusual opportunity to marry the bird’s-eye view that large-scale surveys deliver with the detail and intimacy of laboratory research and in-depth interviews. Davidson could attach a hairnet of electrodes to the scalps of survey respondents to record electrical activity in the brain or slide them into his fMRI when they came to the university for other lab tests. “That’s been a spectacular strategy,” he explained. “I don’t think that MIDUS has at this point even come close to realizing its potential as a unique research enterprise.”
Davidson and his colleagues plan to follow their sample of 331 MIDUS subjects over the next five, ten, twenty years, and beyond. The process is comparable to one of the most famous and ambitious long-term health studies, the Framingham Heart Study, begun in 1948 by the National Heart Institute (now called the National Heart, Lung, and Blood Institute). By tracking the men and women who lived in Framingham, Massachusetts, and then their children and grandchildren, scientists have been able to explore the roots of heart disease. Over the years more than fifteen thousand participants have dutifully submitted to medical examinations, lab tests, and interviews every four years, helping scientists learn, for example, that high blood pressure in middle age was a risk factor for cardiovascular disease later on. Davidson essentially wants to do the same thing, but instead of blood pressure he is looking at emotional responses. “I am particularly interested in how life experience may play a role in modulating brain function, which then will be associated with physical health and illness,” he said. The brain works on every organ in the body, and every organ sends messages back to the brain; we just don’t know the pathways. By discovering the biological connection between the head and heart, Davidson hopes to detect whether the way in which individuals respond to adversity at 50 will predict whether they develop cardiovascular disease at 60.
“I’ve been interested in emotion my entire life,” Davidson told me during my first visit to his office at his laboratory at the University of Wisconsin. Davidson is trim in khakis and a crisp button-down shirt. A wave of gray-speckled black hair surfs across his forehead. He has a low, husky voice that on certain words reveals his Brooklyn roots.
How, he wondered, were these insubstantial, immaterial feelings—fear, anger, guilt, joy—produced? At 14, he was volunteering in the sleep lab at a local hospital, cleaning electrodes and trying to decipher electroencephalography (EEG) recordings of electrical activity in the brain. In high school, he read voraciously and became deeply interested in meditation. While at Harvard working toward a PhD in psychology, he took three months off to travel through India and Sri Lanka. In 1974, as most Americans watched Richard Nixon resign from the presidency, the 22-year-old Davidson and his soon-to-be-wife, Susan, were on a mountain in northern India for a meditation retreat.
He came to teach at the University of Wisconsin in 1984, and has since won a shelf full of awards for his psychological and neuroscience research, as well as a spot on Time magazine’s 2006 list of the hundred most influential people in the world. In 1992, Davidson was surprised and thrilled when Tenzin Gyatso, the fourteenth Dalai Lama, got in touch with him. He had heard of Davidson’s work through the Mind & Life Institute, a nonprofit organization in Boulder, Colorado, where Buddhists and scientists research the brain’s abilities and contemplation. Davidson was on the board of directors.
“He was interested in having neuroscientific research on Tibetan monks who had spent years cultivating their minds,” Davidson said. Behind his desk is a photograph of him with the Dalai Lama in his recognizable saffron and maroon robes. The Dalai Lama wondered whether the monks’ deep and extended meditative training could generate compassion and more positive thoughts. Davidson accepted the invitation to visit Dharamsala, the Dalai Lama’s residence in northern India during his exile from Tibet. In the psychologist’s considerable load of baggage were portable electrical generators, laptop computers, and EEG recording equipment.
After the trip, Davidson said, “I made a commitment to myself . . . that I was going to come out of the closet with my interest in meditation.” He had kept this passion a secret ever since his Harvard professors scorned it. “They patted me on the knee and said, ‘Richie, this is not a good way to start a scientific career.’”
In the years that followed, the scientist and the monk have collaborated on a variety of studies as robed lamas have journeyed to Davidson’s lab to lie on the scanner bed, as I did, and have their brain circuitry scrutinized.
Descartes versus Spinoza
Davidson is bringing the full arsenal of advanced technology to bear on the centuries-old mind-body problem. Since the Enlightenment, Western civilization has hewed to the model that the Parisian René Descartes set forth in the seventeenth century, with the immaterial mind in one realm and the physical body in another. “This I (that is to say, my soul by which I am what I am) is entirely and absolutely distinct from my body, and can exist without it.” Davidson was dissatisfied with this formulation. Emotions were incorporeal, but something in the body had to generate them. They had no substance, yet they could cause your hands to sweat and the back of your neck to tingle. “I was interested in emotion when emotion was in the dustbin of American psychology,” Davidson said of the 1970s and 1980s. “There were probably three people in the academy who were studying emotion and it was considered a real backwater, not at all tractable and really uninteresting. And it just seemed to me that was really an off-base view, because emotions seemed to be so central to everything that is important about our behavior. . . . People thought I was completely off the wall.”
The twentieth century’s infatuation with behaviorism—we are what we do—led scientists to view the brain as a miniature computer, an infinitely sophisticated mechanism for reasoning, calculation, memory, and language. Feelings were unscientific.
The very notion that emotions could be measured or studied in laboratory experiments seemed ridiculous. Besides, who cared? Most scientists did not assume there was any link between one’s emotional state and one’s physical health. And if one existed, the body was the source.
When Davidson embarked on studying the brain in graduate school in 1972, EEGs were state of the art. But in the last fifteen years, neuroimaging, particularly functional magnetic resonance imaging (fMRI) and other imaging methods, have revolutionized the field. Indeed, the influence of fMRIs has been compared to the impact of the telescope on astronomy. Of the sixty-one people employed in his lab, about one-third are physicists who work on new technology and methods. Brain imaging gives neuroscientists a much fuller picture of what goes on in our heads. Although our understanding of how the layer of gray and white matter works is still in its infancy, the glimpse inside has convinced most scientists that the brain and the body are much more intertwined than anyone suspected.
Descartes, it seems, was wrong after all—at least from the st
andpoint of today’s neurologists. It looks like Baruch Spinoza, the moody seventeenth-century Dutch philosopher and excommunicated Jew, who never lived to see most of his work published, was right to argue that the mind and body are not two separate entities but simply different expressions of the same thing. In Spinoza’s cosmology, there is only one unique infinite and indivisible substance, and that is God or Nature. “Spinoza prefigured in a remarkable way some of the ideas on emotion, feelings, and ethics that are now taking shape as a result of modern neuroscience,” said the neurologist Antonio Damasio, author of the book Looking for Spinoza. Our emotions are, in fact, bound to our physical health and critical to our survival.
How that connection operates is still a mystery. What happens inside your body to produce that feeling of frustration when you get stuck in traffic, and how does that frustration cause your blood pressure to rise? How can the circuitry in the brain accelerate heart rate or weaken the immune system? Health psychology is the field that studies the link between emotion, stress, and physical health, but to Davidson “health psychology is a brainless enterprise.”
“These events happen to you in the outside world and somehow they affect your health,” he said. “But what are the mechanisms for how that occurs—that’s never really been asked. From where I sit, the brain has to be in the equation, because the way the social world gets under the skin is via the brain.”
Emotional Resilience
Through a series of experiments, Davidson and a handful of other neuroscientists have helped to upend more than three hundred years of thinking about the dualism of mind and body. In 1996, he and his colleagues published one of the first studies to show that disturbing pictures caused a response in the human amygdala. Davidson found that neural circuits in that region of the brain became particularly busy when people got angry, upset, or depressed. He discovered that negative emotions and stress set off the right prefrontal cortex, while joy and enthusiasm set off circuits in the left prefrontal cortex.
Davidson’s early experiments with monks and meditation suggested it might be possible to purposefully alter the neurological activity in the brain and gain control over one’s emotions. In one study, monks who had spent at least three years alone or about ten thousand hours on a retreat—the “Olympic athletes of meditation”—were monitored as they meditated in a state of “unconditional loving-kindness and compassion.” They all showed an unusually strong pattern of synchronized gamma-wave activity, a movement of brain cells that is generally associated with concentration and emotional control.
Scientists interested in meditation were exploring whether it could induce physiological changes in the brain and the immune system. In 1997, Davidson convinced a few dozen workers at a biotechnology company outside Madison to learn mindfulness meditation, a method rooted in Buddhist practices in which a person trains to control his thoughts, and then identifies and banishes those that produce anxiety. Once a week, for two months, Davidson’s associate brought meditation tapes and Tibetan chimes to the office and led a group of scientists, marketers, lab technicians, and managers in meditation for three hours. Before each session, their brains were wired and measured. Davidson’s team found that the average emotional state of the employees had shifted into a more positive zone—that there were significant increases in activity in several areas of the left prefrontal cortex, the joy center, compared with workers who did not receive any training. One possibility, Davidson hypothesizes, is that neurons in the left prefrontal cortex are capable of blocking disturbing messages sent by the amygdala. Even more intriguing, participants showed signs of strengthened immunity; the number of antibodies they produced after a flu shot were higher than that of the control group. The experiment did not prove that meditation caused the boost to the immune system, but it did suggest that the experience of meditating might accomplish the extraordinary feat of modifying the brain’s structure.
Stephen Kosslyn, a Harvard psychologist who has collaborated with Davidson, said this study “fits into the whole neuroscience literature of expertise . . . where taxi drivers are studied for their spatial memory and concert musicians are studied for their sense of pitch.” Kosslyn was referring to an experiment involving London cabbies, whose famously rigorous training requires that they master 320 routes comprising 25,000 streets. Brain imaging showed that the posterior hippocampus, the peapod-shaped area related to memory, was enlarged. The more experienced the driver, the larger the rear hippocampus. Those drivers might have had bigger hippocampi all along, but Kosslyn believed there was another cause: “If you do something, anything, even play Ping-Pong, for twenty years, eight hours a day, there’s going to be something in your brain that’s different from someone who didn’t do that.”
Davidson is convinced that a cause-and-effect connection exists. “Neuroplasticity”—the ability of the brain to change—“is the most important idea in neuroscience in the last decade,” he said. “More than any other organ in our body . . . the brain is built to change in response to experience.” Scientists agree that the brain is more adaptable than anyone thought. What no one knows is how much more. Davidson argues that with practice people can learn to modify their brain activity through mindfulness training or meditation like the monks, who seemed able to control their concentration and emotions by generating synchronized gamma waves. These “neurally inspired behavioral interventions,” as Davidson calls them, may reduce the danger of stress-related diseases like cardiovascular illnesses and diabetes later in life, as well as the premature aging of our cells. An experiment published in 2009 and financed by the National Institutes of Health suggested this might be possible. Researchers found that high-risk African American patients who meditated over five years were roughly half as likely to suffer heart attacks, strokes, and deaths compared with a group of similar patients who were counseled about diet and lifestyle.
In 2011, a group of scientists at Massachusetts General Hospital reported that they found direct proof that meditation was the cause of alterations in the brain’s structure. People who meditated half an hour every day for eight weeks developed more gray matter, the densely packed outer layer of nerve cells, in the hippocampus and other regions of the brain associated with learning and emotional regulation. At the same time, the density of gray matter in the amygdala, the stress center, decreased. “This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing,” said Sara Lazar, one of the study’s authors at the hospital’s Psychiatric Neuroimaging Research Program.
In Davidson’s eyes, “there is no more effective way to produce localized and specific changes in the brain than behavioral or mental interventions.”
The Middle-Aged Brain and Intelligence
Until the twenty-first century, the prevailing view was that mental decline started in midlife. There were reasons to think so. At around 40, the brain, with its 100 billion neurons, begins to shrink in both weight and volume by about two percent every decade. The ventricles, which contain the fluid that surrounds and cushions each part of the brain, protecting it from knocks and jolts the way an amniotic sac cradles a fetus, grow larger as gray matter disappears. At the same time, the spaces or fissures between the undulating grooves on the brain’s thin outer layer become more defined. Connections between neurons thin out like male-pattern baldness, and the synapses—the places where neurons fire chemical transmitters—become increasingly sparse. The flow of blood and oxygen to the brain also begins to contract ever so slightly. Across the brain’s white matter—those bundles of nerve cell transmitters that are wrapped and insulated in a fatty molecule called myelin—small lesions can sometimes appear. Myelin itself can deteriorate and the brain’s ability to repair the DNA inside weakens. Most vulnerable of all is the prefrontal cortex, the brain’s executive office, where high-level planning and organization of complex behaviors take place.
Such physical alterations sou
nd ominous and seem to point to irrevocable loss. But that is far from the whole story. If mental agility declines with age, why then is wisdom, one of the most valued measures of brain functioning, consistently associated with old age?
Scientists began questioning assumptions about aging and mental decline in the late 1920s and early 1930s. Edward Lee Thorndike, a psychologist who helped found the modern field of educational psychology, was one of the first to challenge conventional thinking about declining brainpower. Drawing on his experience with testing subjects for the U.S. military in World War I, Thorndike later conducted research on adult learning, asking people between 14 and 50 to perform different tasks like memorizing passages of poetry. He concluded that there were no meaningful differences in the abilities of 25- and 45-year-olds, the early years of middle age.
In the 1970s, a handful of psychologists pointed out that conclusions about aging and mental losses were often based on the frailest and most impaired segment of the population, the five percent of elderly people who lived in nursing homes. Like the originators of the MIDUS strategy, they decided to examine what extra abilities might accompany aging instead of searching only for deficits—to look at the half of the glass that was full.
Other studies had design flaws. Some differences in test results between younger and older adults were due to the particular vocabulary used on an exam or a familiarity with certain professions rather than with age. Testing memory in the elderly and college students by asking them to remember pairs of nonsense words skewed against older people. Students, accustomed to competing in all sorts of tests, were keen to do well, while the elderly were not especially motivated to work hard to remember meaningless terms.
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