Successful Aging: A Neuroscientist Explores the Power and Potential of Our Lives

by Daniel J. Levitin

Learning how to avoid certain environments, habits, and stimuli that influence our personalities in negative ways is a crucial part of aging well.

Our bodies react to insults, both psychological and physical, by releasing cortisol, the stress hormone. Cortisol is very useful if you need to invoke the fight-or-flight response—say, when you’re confronted by an attacking tiger—but it is not so useful when you’re dealing with longer-term psychological challenges such as loss of respect.

In contrast, when we’re actively engaged and excited about life, our levels of mood-enhancing hormones such as serotonin and dopamine increase, and the production of NK (natural killer) and T cells (lymphocytes) also increases, strengthening our immune systems and cellular repair mechanisms.

Now, for reasons we don’t yet understand, AD is selective with regard to sex. Sixty-five percent of patients are women, and a woman’s chances of getting AD now exceed her chances of getting breast cancer.

Fending off Alzheimer’s, he says, involves five key components: a diet rich in vegetables and good fats, oxygenating the blood through moderate exercise, brain training exercises, good sleep hygiene, and a regimen of supplements individually tailored to each person’s own needs, based on blood and genetic testing.

Parents living in poverty, suffering from mental illness, or facing great stress are much more likely to be fatigued, irritable, and anxious. “These states clearly compromise the interactions between parents and their children,” he says. And, subsequently, they compromise their children’s brain chemistry and resilience in the face of setbacks—even future ones.

Nurture (or lack thereof) early in life affects the development of a number of brain systems selectively, such as glucocorticoid (GLUE-co CORT-ick-oid) receptors in the hippocampus, which are a primary component of the stress response, part of the feedback mechanism in the immune system that reduces inflammation.

More cuddles and hugs go a long way, particularly in the vulnerable first year of life. As parents (and grandparents and teachers), our choices about how we raise our children in their first years will have a far greater impact on what their last years look like than we might previously have recognized.

This led me to bridge two areas that have maintained separate intellectual traditions—developmental neuroscience and individual differences (personality) psychology. The more I study the intersection of these two, the more intrigued I am at how they can help us to understand the aging brain and the choices all of us can make to maximize our chances of living long, happy, and productive lives. The intersection of these two scientific fields, and how they apply to aging, is the core theme that runs throughout Successful Aging, and something that no one else has written about for a popular audience.

No matter what age we are, our brains are always changing in response to pressures from genes, culture, and opportunity. The choices we make dictate much of the lives we lead.

Throughout this book, I’ll be reinforcing the lifestyle concept that we can change our personalities and our responses to the environment, while continually adapting to the random and unpredictable things life throws at us. This concept has five parts: Curiosity, Openness, Associations, Conscientiousness, and Healthy practices, what I call the COACH principle.

In fact, the biggest single determinant of living a productive and happy life is something that you’re born with (partly) and something that you can decide to change: your personality.

Among the most solid findings is that a child’s personality affects adult health outcomes later in life.

Childhood personality traits, assessed in elementary school, predict a person’s lipid levels, blood glucose, and waist size forty years later. These three markers, in turn, predict risk for cardiovascular disease and diabetes. The same childhood traits even predict life span.

depending upon the function and the environmental context, behavior change can be pervasive and rapid at all ages. In fact . . . the rate of change is greatest in infancy and old age.

we are less shaped by character traits than we think, and more than we realize by the circumstances that life deals us—and our responses to those circumstances.

We think of our genes as influencing physical traits, like hair color, skin color, and height. But genes also influence mental and personality traits, such as self-assuredness, a tendency toward compassion, and how emotionally variable we are.

Your genes, then, give you a kind of life script with only the most general things sketched out. And from there, you can improvise. Culture affects the ways you interpret that script, as do opportunity and circumstance. And then, once you interpret the script, it influences the way others respond to you. Those responses in your social world can change your brain’s wiring and chemistry, in turn affecting how you’ll respond to future events and which genes turn on and off—over and over again, cascading in complexity.

Culture is a potent factor in who we become.

The Big Five dimensions are: Extraversion Agreeableness Conscientiousness Emotional Stability versus Neuroticism Openness to Experience + Intellect (also called Imagination) Each of these categories includes many dozens of individual traits.

Whenever genes, situations, or therapy changes our personalities, they must do so by changing the brain. In that sense, all personality differences are biological, regardless of whether they are influenced by genetics or not, because they must go through the brain.

There are a number of ways in which the natural aging process itself tends to cause some personality changes. In a meta-analysis of ninety-two research papers, covering the life course from age 10 to 101, 75 percent of personality traits studied changed significantly after the age of forty and well beyond sixty.

Conscientiousness, Openness, and Extraversion decreased during old age, whereas Agreeableness and Emotional Stability increased substantially.

Aspiring to a healthier lifestyle may thus lead to personality change—an increase in self-control, methodicalness, and conscientiousness.

Trying something new later in life, like competitive sports, business enterprises, or artistic endeavors, can dramatically increase both your quality of life and how long you live. Openness and curiosity correlate highly with good health and long life. People who are curious are more apt to challenge themselves intellectually and socially and reap the rewards of the mental calisthenics that result. They are also more likely to be interested and engaged, which makes them more fun to be around, and interacting with others socially is a good way to stay mentally agile and alert.

Perhaps the most important traits to foster and develop throughout the life span are those in Factor III, Conscientiousness.

One tangible thing that we can all do to avoid misjudging others is to exercise compassion, to allow for the possibility that you might be wrong in attributing a trait to someone’s behavior. Indeed, this is the core principle at the heart of both social psychology and the teachings of the Dalai Lama. “Compassion is the key to happiness,” he says. “We are a social species and our happiness is defined by our relationship with others.”

Curiosity, Openness, Associations (as in sociability), Conscientiousness, and Healthy practices are the five lifestyle choices that have the biggest impact on the rest of our lives.

every decade after our fortieth birthday, our brains spend more time contemplating our own thoughts versus taking in information from the external environment.

Memory can indeed seem like a puzzle with many missing pieces. We rarely retrieve all the pieces, and our brains fill in the missing information with creative guesses, based on experience and pattern matching. This leads to many unfortunate misrecollections, often accompanied by the stubborn belief that we are recalling accurately. We cling to these misrememberings, storing them in our memory banks incorrectly, and then retrieving them in a still-incorrect form and with a stronger (misplaced) sense of certainty that they are accurate.

Only some things that you experience get stored in memory. This is because one of the evolutionary functions of memory is to abstract out regularities from the world, to generalize.

abstraction occurs without our conscious awareness, and it accounts for one of the most widespread traits that oldsters have: wisdom. From a neurocognitive standpoint, wisdom is the ability to see patterns where others don’t see them, to extract generalized common points from prior experience and use those to make predictions about what is likely to happen next. Oldsters aren’t as fast, perhaps, at mental calculations and retrieving names, but they are much better and faster at seeing the big picture. And that comes down to decades of generalization and abstraction.

Generalization promotes cognitive economy, so that we don’t focus on particulars that don’t matter.

Our memory systems form a hierarchy. At the highest level are explicit memory and implicit memory. They contain what they sound like—explicit memory contains your conscious recollections of experiences and facts; implicit memory contains things that you know without your being aware of knowing them.

Semantic memory, your general knowledge store, is all those things that you know without any memory of when you actually learned them.

In contrast, episodic memory is all those things you know that involve a particular incident or episode.

This is one of the rules of memory that is now well established: We tend to remember best the episodic component of those things that were imprinted with an emotional resonance, positive or negative, regardless of whether the learning would have normally become semantic or episodic.

Two particular brain regions, crucial to some kinds of memory, are the ones that decay and shrink with age and with Alzheimer’s disease: They are the hippocampus (Greek for seahorse, because its curved shape resembles that sea creature) and the medial temporal lobe (neurology-speak for the middle part of a structure just behind and above your ears). The hippocampus and medial temporal lobe are important for forming some of the kinds of explicit memory, and they’re not needed for implicit memory.

The hippocampus is also necessary for storing spatial navigation and memory for places.

Any distraction—a new thought, someone asking you a question, the telephone ringing—can disrupt short-term memory. Our ability to automatically restore its contents declines slightly as we age with every decade after thirty.

This is not to say that Alzheimer’s- and dementia-related memory impairments are fiction—they are very real, and very tragic for all concerned—but every little lapse of short-term memory doesn’t necessarily indicate a biological disorder.

This is how memory works in the brain—as soon as you retrieve a memory, it becomes editable, just like a text document; it enters a vulnerable state and can get rewritten without your intent, consent, or knowledge.

And yet, the autobiographical memory system is prone to huge distortions. It’s a goal-oriented system. It recalls information that is consistent with your goals or perspective. We all tend to recontextualize our own life stories and the memories that formed them, based on the stories we tell ourselves or others tell us. Our original memories become corrupted, in effect, to conform to the more compelling narrative.

Memories can also be affected and rewritten by the mood you’re in.

Another way that our memories are defective is that we often store only bits and pieces of events or facts, and then our brains fill in the missing pieces based on logical guesses. Again, our brains do this so often that we don’t even notice that they’re doing it.

Human memory makes logical inferences from the available information, and it delivers them to you with a potent mix of fact and confabulatory fiction.

Our memory for perceptual details can be strikingly accurate, particularly in domains we care about.

context, is likely to bring back a stream of associated memories. Our memories are therefore associative. The events that constitute them link to one another in an associative network.

That underlying process is multiple-trace theory, or MTT. Every experience lays down a unique trace, and repetitions of an experience don’t overwrite earlier traces; they simply lay down more, near-identical but unique traces of their own.

The beauty of MTT is that it unifies explicit and implicit memory, and semantic and episodic memory. There might be many different systems, but they are governed by one process. That one process stores episodic and semantic traces, and then abstract knowledge as such does not have to be stored but can be derived from the pool of traces of specific experiences.