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

by Daniel J. Levitin

Navigating the complex mores and potential pitfalls of dealing with another human being, someone who has their own needs, opinions, and sensitivities, is about the most complex thing that we humans can do. It exercises vast neural networks, keeping them tuned up, in shape, and ready to fire. In a good conversation, we listen, we empathize. And empathy is healthful, activating networks throughout the brain, including the posterior parietal cortex and inferior frontal gyrus.

Congresswoman Maxine Waters, who represents the Forty-Third Congressional District in Los Angeles, California, is serving her fifteenth term in the House at age eighty-one. She captured the attention of the entire country in 2018 and 2019 as the chair of the House Financial Services Committee. While she draws the praise of Democrats and the ire of Republicans, everyone on both sides of the aisle regards her as calm, collected, powerful, and brilliant. Love her or hate her, she is a force to be reckoned with. And she prides herself on reaching across generations. “We moan and groan all the time about a lack of involvement of young people,” she said. “But they have taught me a lot about what moves them. It seems like all they are looking for is some honesty and some truth and somebody that they can believe in.”

Aging has beneficial effects on our social behavior.

Surround yourself with people who are better than you at something but who don’t lord it over you.

Spend time with people who encourage you to grow, to explore new things, and who take joy in your successes.

when you can, go outside. Go outside. Go outside.

Many people assume that pain simply gets worse as we age, but this isn’t true—it peaks and then falls off. Chronic pain increases and peaks in our fifties and sixties, and then declines in our seventies and older. These numbers could arise because older adults become more stoic and stop complaining about it, or it could be that they simply don’t have it anymore.

The most obvious reason we have pain is that for thousands of years it has given us a survival advantage—it causes us to protect that part of our bodies that has been injured, giving it a better chance to heal.

Pain serves as an essential warning signal.

Acetaminophen (aka Tylenol) has been found to be the least effective for arthritis, but that makes sense—it is not an anti-inflammatory and is not interchangeable with, for example, ibuprofen (e.g., Advil and Motrin). Acetaminophen is a pain reliever and reduces fever. If you have a swollen ankle, it probably won’t help as much as an anti-inflammatory.

There is some early evidence that yoga can bring real and lasting pain relief.

Faulty or misaligned internal clocks are significant contributing factors in Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, and in depression, obesity, diabetes, heart disease, and cancer. With that as a foundation, we’ll visit important practical things you can do to make the most out of three basic biological processes: diet, movement, and sleep.

Circadian rhythms are the product of biological clocks, an evolutionary adaptation in response to the earth’s twenty-four-hour rotation period. They allow our bodies and minds to predict what will come next, so as to be better prepared for different situations and circumstances. For example, predicting when the sun will rise allows the brain to release wake-up chemicals (such as orexin, dopamine, and norepinephrine) and to suppress the drowsiness chemicals (such as melatonin, adenosine, and GABA) that might make us want to roll over and go back to sleep. The inner clock lets us wake up in the morning refreshed and ready to go.

Plants use photosensitive internal cellular clocks to detect the length of days. When they sense the shorter days of autumn, the clocks activate genes that signal the plant to produce seeds and drop its leaves. When the clocks sense longer days in the spring, the plants grow back their leaves, along with flowers or fruit. Biological clocks help plants prepare for sunrise by raising their leaves, tilting them toward the sun, and preparing their internal factories to perform photosynthesis, converting sunlight into nutrients. At night, clocks orchestrate the opening and closing of leaf pores and the nighttime folding of leaves to prevent water loss. If the clocks are regulating plants, mold, and mollusks, you can imagine the complexity of the various roles they play in our functioning. They also exert a large influence on aging—so much so that when tissue from the biological clocks of young animals has been transplanted into older animals, the older animals live longer.

Light, whether it arrives from the rising sun or that little blue light on your cell phone charger, can turn particular genes on and off, changing the timing of when they produce the proteins that influence the biological clock and our circadian rhythms. Daylight or lack of it can speed up or slow down the circadian rhythms.

When May Be as Important as What What you eat, how much you exercise, and how much you sleep are important, but in the past few years, neuroscientists and chronobiologists (people who study biological clocks) have come to understand that when you eat, when you exercise, and when you sleep may be just as important. This is particularly true of older adults. The twelfth-century philosopher and physician Moses Maimonides understood the importance of when to eat, as well as how much. His advice for living a healthy life was to “eat like a king in the morning, a prince at noon, and a peasant at dinner.”

Eating at different times each day, or at times that are out of sync with your circadian rhythms, can lead to obesity, metabolic syndrome, diabetes, and other problems. Your mother was right when she told you to eat a big breakfast and to have dinner at a fixed time.

Research on the microbiome is still in its infancy, but early evidence points to the possibility that what and when you eat can influence the microbiomic clock (the circadian rhythms of your microbioata) and, further, that your microbiome can send information up to the master clock in your SCN to influence its timing.

As you probably know, people differ in terms of the time of day when they are most fresh and alert.

In popular parlance, I’m an early bird; my wife is a night owl. We have different chronotypes. Different chronotypes have a genetic basis, but they also interact with environment and experience. Years of staying up late, consistently, and exposure to blue light beyond sundown can cause changes in gene expression that shift your chronotype at the genetic level.

I’m not advocating a return to homes without artificial light—just a better understanding of the effects they have on us so that we can create better home environments. The use of home lighting, and most recently of computer screens, clocks, and various devices that emit blue light, has created a population of night owls. Currently only 30 percent of the population sleep best by going to bed before midnight. That means 70 percent of the population can’t get to work by eight or nine A.M. without waking their body up before it is biologically ready.

scientists identified those workers who were early birds versus night owls and gave them different shifts so that their work schedules aligned with their internal clocks. Once their chronotypes were aligned with their duty shifts, workers enjoyed 16 percent more sleep, almost a full night’s length over the course of the week.

Why do individuals have different chronotypes? To quote Shakespeare, “Some must watch while some must sleep.” From an evolutionary standpoint, consider what life was like for our ancestors ten or twenty thousand years ago. Sleep was necessary for survival, and yet it was a time when we were especially vulnerable to attack by animal predators and violent humans, as well as the occasional hurricane or erupting volcano. The sentinel hypothesis is that when living in groups, animals share the task of nighttime vigilance, some watching over those who sleep.

When we’re young, the biological clock is more flexible, malleable, and it can react to environmental changes quickly. As we get older, resetting the biological clock can take longer—much longer.

Generally, it takes your body one day of recovery or planning per one hour of time-zone shift when traveling east, and half a day per one hour of time-zone shift when traveling west. This is a best case scenario.

Light therapy and melatonin treatments are the most effective means of resetting the circadian clock, especially in the aged. They are also effective in people with Alzheimer’s-related or mild cognitive impairment. It’s possible that these treatments may also prevent or delay the onset of Alzheimer’s disease itself.

In one review, melatonin use in early-stage Alzheimer’s supported findings that sleep quality was improved, sundowning was reduced, and the progress of cognitive decay was slowed. In four studies of melatonin treatment, cognitive performance improved, and agitated behavior was reduced.

Light-therapy lamps that simulate a gentle dawn are readily available and cost less than one hundred dollars. Increasing light intensity and optimizing the wavelength of light can compensate for some of the organic deterioration of the SCN and related chemical circuits that accompany aging. But the light therapy must be done at the correct time of day—upon waking—and it must be done consistently. Everyone is different, but by experimenting with different intensities and durations of light exposure, you can arrive at the most effective treatment. You may have heard of seasonal affective disorder (SAD), which causes mood and concentration disturbances and is triggered by the shorter, grayer days of winter. Many of the lamps sold for light therapy are branded and marketed as SAD lamps.

Sleep-medicine specialist Alfonso Padilla at UCLA recommends taking just 0.25–0.5 mg to resynchronize your biological clock. This amount mimics the physical levels that your body naturally releases (when everything is going well). Melatonin’s sleep-promoting action works as a step function, meaning that if you get enough of it, more won’t help (and could be harmful). Although over-the-counter products commonly available often contain 5–10 mg (and at least one manufacturer sells 60 mg tablets), overdosing can cause extreme drowsiness the next day and disrupt your sleep cycle for a week or more.

Melatonin levels tend to rise about fourteen hours after waking. If you get eight hours’ sleep every night and wake at six A.M., that means your melatonin levels will naturally rise around eight P.M., and you’ll start to get sleepy and go to bed two hours after that, around ten P.M. If it takes about an hour for a melatonin pill to be absorbed into your bloodstream, that means taking one about three hours before bedtime.

The next most effective treatment, after light therapy and melatonin, is moderate late-afternoon or early-evening exercise, like going outside for a walk. The combination of all three is the best.

Sports that typically conduct early-morning training, such as rowing and track, tend to attract those individuals with an early-morning chronotype. Sports that are typically done in afternoons and evenings, such as water polo, volleyball, cricket, hockey, and soccer, attract late-chronotype athletes.

Some studies show that peak performance in grip strength, running, jumping, oxygen uptake, and muscle function tends to occur between four P.M. and eight P.M. in the athlete’s home time zone. Similar peaks have been found for football, swimming, and cycling.

I’ve touched on the ways in which the effectiveness of eating, exercise, and sleep in maintaining optimal health and vigor is dependent on our bodies’ natural rhythms. You can see that they are connected through circadian rhythms; their decoupling can cause problems, especially in old age, when our bodies are less resilient. In

The drive to carve out a special selection of foods to promote weight loss or health has been around as long as recorded history. In ancient Greece (home of the Mediterranean diet), the great physician Hippocrates advised overweight citizens to follow a strict regimen of “exercise and vomiting.” William the Conqueror, beginning around 1080, followed an all-alcohol diet. (He later died in a horseback riding accident.) In the early 1800s Lord Byron followed a vinegar diet. The early 1900s saw the tapeworm diet. (Yes, it is what it sounds like. The idea is that tapeworms would consume some of the food you eat and then you just expel the tapeworms—what could possibly go wrong?)

Stanford nutrition scientist Christopher Gardner notes that “no matter how crazy a diet might be, it will work for someone if enough people try it. . . . If you give it to 100 people, it might work for only two of them, but the people promoting the diet don’t test it that way; they simply focus on the two successful stories.” Maybe what’s really going on is that following a diet, any diet, causes you to pay more attention to the foods you’re eating—to engage in mindfulness—and that’s where their effectiveness is, not in the particulars.

Herbal remedies, vitamins and minerals, and dietary supplements are often marketed as “natural” products, but natural doesn’t always mean safe. Cow dung is “natural.” In one study, 20 percent of Indian-manufactured Ayurvedic medicines tested contained toxic levels of lead, mercury, and arsenic. The Mayo Clinic provides a helpful guide for consumers who are contemplating alternative treatments.

High-density lipoprotein (HDL, the “good” cholesterol) picks up excess cholesterol and takes it back to your liver, which then removes it from your body. Unhealthy eating habits and obesity can raise your bad cholesterol levels. Lack of physical activity can lower your good cholesterol levels.

LDL levels naturally rise with age, making healthy lifestyle habits increasingly important, especially after age fifty. There is a genetic component as well—the rate at which bad cholesterol climbs and the ability of physical activity to increase good cholesterol are partly inherited.

Diets high in soluble fibers are good because the fiber binds to the LDL cholesterol molecules in the digestive system and drags them out of the body before they get into circulation. Some good sources of soluble fiber are oats (oatmeal, Cheerios, Trader Joe’s O’s), barley and other whole grains, beans (including soy beans and soy milk), high-fiber fruits (apples, strawberries, citrus; the pectin they contain is a soluble fiber), eggplant, okra, fatty fish, liquid vegetable oils, and nuts (just two ounces of nuts a day can lower LDL by 5 percent). Diets high in omega-3 fatty acids, as found in fatty fish, seeds (especially chia, flaxseed, and hemp), nuts (especially walnuts), and olive and canola oils also lower LDL and reduce the risk of heart disease by 7 percent. Insoluble fibers (wheat bran, vegetables, and whole grains) are also healthy because they prevent constipation and diverticulitis.

Some of the neural benefits that are found with fasting also occur with vigorous exercise. The neurochemical changes are similar: Both stimulate the production of brain-derived neurotrophic growth factors (BDNFs). Fasting stimulates the production of ketones, an energy source for neurons. Fasting can increase the number of mitochondria in neurons, which helps them produce more energy.

For now the best bet for increasing longevity and the event horizon for the detrimental effects of aging appears to be just eating less, and there are many ways to do this, although we don’t yet know which is going to be the most effective: reduced calories throughout the day; one fast day a week; two fast days a week; fasting every other day; fasting two weeks a year; no dinners; one month of juice fast every year; and so on. At first it can feel awful, but many people find they can build up to it and get used to it. Many researchers I know have begun to do it. Jeffrey Mogil fasts one day a week. Cynthia Kenyon gave up carbs. I don’t eat if I’m not hungry and I skip dinner a couple of times a week. Mark Mattson does intermittent fasting—reducing the frequency of meals. There are, of course, dangers in following an improvised or ad hoc calorie-restrictive diet.

When you do eat, certain foods show up in study after study as being healthful. These include virgin olive oil, which is rich in monounsaturated fatty acids—the good fats. Consuming olive oil (around 3 tablespoons a day) is associated with relieving oxidative stress on cells and regulating cholesterol and anti-inflammatory activity. Cruciferous vegetables, including Brussels sprouts, broccoli, cauliflower, kale, cabbage, and bok choy, have been shown to have protective effects against many forms of cancer and can even inhibit the progression of some cancers. They do this by initiating cellular defense mechanisms and modifying cancer-related genes. Glucosinolates and 3-carbinol are the health-promoting agents in cruciferous vegetables. Another component of the Mediterranean diet is oily fish, such as sardines and anchovies. These contain the omega-3 fatty acids that are known to be essential in the development and maintenance of brain and retinal tissue, as well as for myelination.

Many cognitive and physical benefits are claimed for a number of diets, including the DASH, MIND, and Mediterranean diets, but there is little evidence to support them.

Lack of protein can cause serious problems with your brain, muscles, and immune system.

Hydration is something most of us don’t think about, but it is essential for cellular and brain health. Often if you notice yourself feeling fatigued, this is the first sign of dehydration. Other symptoms include headaches and nausea. Dehydration is a medical condition—it is not thirst. Thirst is just a symptom that may or may not be present when you’re dehydrated.

There are several oral rehydration solutions available over the counter. You might keep some in your purse or briefcase, in your desk at work, and at home, and take it about twice a week if you’re prone to dehydration. If you have a cold or flu, drink two a day. If you feel lethargic, or after a particularly hot day, intense workout, or drinking alcohol, you might take some.

There is an emerging body of evidence that the gut microbiome also affects cognition, behavior, and brain health. This is cutting-edge stuff and the story is still being written. We already know that serotonin is an important neuroregulator of mood, memory, and anxiety. It turns out that 90 percent of the serotonin in the body resides in the gut, and it is manufactured there by bacteria such as Candida, Streptococcus, Escherichia, and Enterococcus.

Gut bacteria have been linked to mental well-being and depression. People who lack two particular bacteria, Coprococcus and Dialister, are more likely to be depressed, and those who have normal levels of them report a higher general quality of life. Coprococcus is associated with dopamine signaling, and it also produces butyrate, a fatty acid that is an important anti-inflammatory agent; increased inflammation has been linked to depressive symptoms. A third bacterium, Faecalibacterium, also produces butyrate and is found in people who report a higher quality of life.

The gut microbiome can become out of balance, leading to a condition called dysbiosis. The most commonly known cause of dysbiosis is taking prescription antibiotics for an infection. These can kill not just the disease-causing bacteria but beneficial gut bacteria as well. Dysbiosis can also be brought on by unhealthy lifestyle behaviors, such as irregular eating times and high-fat diets. When we’re younger, the effects are so subtle we don’t notice. When we’re older, the effects can be debilitating.