Scientists attribute the debilitating disorder to the gradual accumulation between brain cells of a toxic protein, beta-amyloid, that blocks the transmission of information from cell to cell, wipes out synapses, and disrupts basic neuron function, leading to cell death. Inflammatory processes are also involved in memory loss.
The vast majority of Alzheimer's cases—over 99 percent—occur spontaneously; they are not linked to genetic factors. But they are linked to obesity. Researchers find that the same lifestyle choices that lead people to become obese or develop heart disease also increase the risk of developing dementia.
It comes down to this: Choices we make throughout life about what we put in our bodies may protect against Alzheimer's, or delay its onset. At the very least, says neuroscientist Gary Wenk, "We can slow down the time that it takes for someone to get symptoms." Professor of psychology, neuroscience, and molecular virology, immunology, and medical genetics at The Ohio State University, Wenk is author of the book Your Brain on Food.
Heading off dementia, he insists, starts with what we eat. Food should be thought of the same way as the drugs we put in our body. They're all made up of chemicals. Everything we consume prompts a reaction in the brain. Picking the right foods can minimize damage to neurons and preserve a healthy mind as you age.
Public Enemy Number One
It's oxygen—you know, the molecule without which you can't live. We have a complex relationship with the element: We desperately need it to breathe, and it is absolutely essential for metabolism, that is, converting the food we eat into energy. However, it causes us to age.
Proteins, fats, and carbohydrates are made up of chains of carbon atoms bonded together in a variety of ways. The body is built to break down the chains into the basic sugar glucose, which actually fuels our cells. Left over are carbon bonds that are cleared out by every breath we take—inhale oxygen, which binds with carbon to escort it out the body, exhale carbon dioxide. Biology 101.
Unfortunately, rogue, unbound oxygen molecules—free radicals—that invariably form during energy metabolism are toxic to body cells, essentially causing them to rust over time. Normally, the hemoglobin molecule in blood regulates oxygen levels throughout the body so that cells are not overexposed to it. Aging also weakens our natural defenses against free radicals, putting all our cells (including neurons) at risk.
Antioxidant molecules are abundant in nature; plants maintain elaborate systems of them, and they are found notably in colorful fruits and vegetables (compounds like vitamins A, C, and E, beta carotene, and capsaicin, the spice in chili peppers). A diet rich in antioxidants combats the oxidative stress we are constantly under.
In the brain, antioxidants slow neurodegeneration. "The chemicals that give fruits their color are exactly what we want to protect us from oxygen," says Wenk. In fact, by eating foods rich in antioxidants, we're taking advantage of the way another life-form has devised to defend itself against environmental harm. From their own sources of proteins and carbohydrates, plant cells synthesize the chemicals we recognize as antioxidants as shields against bacteria, viruses, and the oxidative stress resulting from exposure to ultraviolet light or the toxin ozone.
Because of the basic similarities of evolved life processes, the plant protectors can also help human cells from showing the wear and tear of existence. Blueberries, broccoli, grapes, prunes, strawberries, spinach, artichokes, apples—all contain large amounts of antioxidants, as do herbs and spices like rosemary, turmeric, thyme, and oregano. Bright, yellow-orange turmeric is a classic ingredient in the curries that are a staple of Indian cooking. Please note: The incidence of Alzheimer's disease in India is one-sixth that of the U.S.
Adding antioxidant-rich foods to your diet is a fine hedge against dementia. But you need to add more than one. There are thousands of antioxidants—scientists haven't even come close to discovering them all, although they are now testing some of them, including turmeric, as therapeutic agents. Each has a unique combination of chemicals that fight oxidative damage in a distinctive manner.
Regularly consuming a battery of antioxidants through daily diet negates the need for vitamins and supplements, which, Wenk points out, offer little protection against Alzheimer's disease. "There's a parallel between our health and cancer, which, we've learned over the past 50 years, is something people get when they're exposed to low doses of something day after day," he says. "Every day, your brain (and body) ages a little bit, and every day there's an opportunity to help it not to."
What Your Brain Wants
First thing in the morning, after several hours of sleep, the brain is running low on glucose. Once awake, it's on the hunt for exactly the foods that deliver heaps of glucose. In short, it's jonesing for fries.
Fast carbohydrate sources prompt bursts of insulin, a peptide (or small protein) secreted by the pancreas in response glucose. Insulin's job is to get glucose into cells; in the brain, it ushers glucose into needy neurons. Exquisitely sensitive to glucose levels, insulin rushes into the bloodstream; rapid spikes in insulin levels in response to sugary foods are followed just as quickly by rapid declines in the hormone, as it pushes glucose into cells for energy. The result: You're hungry again a couple of hours later. So, you snack. (A bag of potato chips, perhaps?)
Eating big meals loaded with simple carbohydrates (high glycemic meals), a common practice in the U.S., can, over time, undermine the insulin system. So critical is this metabolic mechanism that the health of the insulin system predicts how well you're aging. When insulin signaling isn't working properly and glucose isn't getting into cells—insulin resistance—neurons are deprived of the fuel they need for cognition and self-control. Insulin resistance is correlated with increased formation of toxic beta-amyloid in the brain and with type 2 diabetes.
Eating several big meals a day compounds the risk. Instead, Wenk suggests eating only one big meal a day, and its timing is crucial: a varied breakfast. Edibles providing a variety of nutrients that are digested slowly yield sustained energy for the day in a way that minimizes wear and tear on the body. That way, you'll require only small refueling bites the rest of the time you're awake. Envision a breakfast that marries complex carbohydrates, such as oatmeal, a whole grain bagel, grapefruit, or low-fat yogurt; a burst of antioxidants, perhaps in the form of orange juice; and eggs or, say, turkey sausage for protein. You could even throw in a doughnut to give your brain the simple sugar punch it so desperately wants.
Don't forget to add coffee or tea. Your brain will also crave caffeine when you wake. Throughout the night, levels build up of the neurotransmitter adenosine, and that buildup blocks the function of neurons that make another neurotransmitter, acetylcholine, which is critical for paying attention and learning. Caffeine frees up acetylcholine neurons to make you more functional. Coffee and tea also contain antioxidant and anti-inflammatory compounds known as flavonoids.
Coffee protects your brain against aging in yet another way. People who drink five or more cups a day are 85 percent less likely to develop Parkinson's disease, which, in addition to its trademark tremors, can also cause dementia. The downside to a lot of caffeine is insomnia, jitteriness, and stomach problems. Good for the brain. Not so good for the body.
A Nibble Here or There
After breakfast, Wenk recommends, graze every hour or half hour, as needed, on fruit or nuts; due to their fiber (fruit) and fat (nuts) content, they release their payload at a stately pace and are metabolized slowly. There's no rush of chemicals to the brain. Lunch, Wenk says, should be low-fat and colorful. Think: chicken salad or fish and steamed vegetables. The afternoon should hold more nibbles followed by a small dinner.
Free yourself from the notion that dinner consists of appetizer, entree, and dessert. Most calories should be consumed up front, to give the brain the energy it needs to get through the day. Dinner, Wenk explains, is an opportunity to load up on compounds not eaten earlier—foods with omega-3 fats, such as salmon, kiwi, or walnuts, which help neurons maintain their structural integrity. Says Wenk: "As far as the brain is concerned, the purpose of eating after 5 p.m. is to get enough nutrients to get you through the night without waking up."
All in Moderation
Even with the damage oxygen inflicts on the body, you can't not eat. That said, one very workable strategy for avoiding oxygen overexposure is simply to eat less. "Then you don't have to eat so many other things to protect you from the foods you did eat," Wenk observes.
Caloric-restriction diets (eliminating up to 40 percent of food intake per day) not only slow the aging process but offer cognitive benefits. The trade-off, however, is less energy, less activity, weak bone structure, and frailer musculature. To benefit from such a regimen takes a little experimentation. If you typically eat 2,000 calories a day, try cutting back to 1,600 and seeing whether you still have enough energy for some exercise. Since exercise requires energy—and, thus, oxygen—Wenk recommends two hours a week of aerobic exercise, or as little as three 20-minute walks per week.
When epidemiologists interview older people, those who maintain good mental and physical health often don't report being extremely active, which could cause long-term joint pain that also contributes to aging. "What people tell us is they were frequently active, did a little something everyday, and that seems to have biased them to live longer," Wenk explains. "They didn't tend to overeat, they didn't tend to overexercise. In fact, they didn't tend to live lives of extremes at all. It was always the moderation."
The Age Factor
Your age might also influence the zeal with which you consider adopting Wenk's brain-saving lifestyle. It is, he insists, like investing in the stock market: "If you start early, in your 30s, then you've got time to do the right things. In your 60s, there's less time to invest in your health."
Genetic makeup is a consideration in when to adopt a brain-saving diet. Heritability of Alzheimer's disease, though rare, appears to travel through the female line, Wenk points out. Anyone whose grandmother, mother, or aunt has developed dementia should consider the protective power of immediate lifestyle change.
Since metabolism slows with age, leading many to gain weight later in life, your best brain-saving regimen may be dropping the number of calories you're taking in. Taking weight off is a crucial step in saving one's brain. "The sooner you get started the better," advises Wenk.
In general though, thirtysomethings might begin to incorporate more colorful vegetables into their diet, or shift the bulk of their food intake to earlier in the day. By the time people hit 60, they might do well to remember the lyrics to the Rolling Stones' hit "Ruby Tuesday":
"There's no time to lose, I heard her say/Catch your dreams before they slip away/Dying all the time/Lose your dreams and you will lose your mind/Ain't life unkind?"
What About Our Vices?
Don't assume that a brain-saving diet forbids goodies such as alcohol and chocolate. If consumed in moderation—of course—even daily, such indulgences can be beneficial.
Epidemiologists have evidence that alcohol protects against Alzheimer's disease. It's a powerful solute that helps dissolve fat in the body, offering cardiovascular protection that benefits the brain as well. The trick is not to consume so much that the liver becomes fatty. Red wine contains, in addition, the antioxidant resveratrol, effective against aging. Prefer beer? The hops that give beer its color also have antioxidant properties. Have a bite to eat first; it helps slow absorption of alcohol so you don't get drunk.
That bite could be a small bar of chocolate. "There's no better compound in nature in terms of flavonoids," says Wenk. Dark chocolate is best, due to its high cocoa content. Men who eat chocolate regularly, in fact, are known to live longer than men who do not.
As we age, our bodies don't harness the anti-inflammation powers of chocolate and other foods as well as they once did. There is, however, a substitute, shown to protect against Alzheimer's disease among people in their 60s and 70s. It's marijuana, studies in Wenk's lab show. Inhaled, the chemicals in marijuana travel easily into the brain, where they reduce inflammation and also stimulate neurogenesis, the birth of new neurons, another ability that attenuates with age. Wenk finds that a puff a day is sufficiently anti-inflammatory, although he doesn't encourage anyone to start smoking weed. Aside from the fact that it's not legal in most of the U.S., "it might cause the munchies," he says, "and that's not going to help."
What to Ditch from Your Diet Now
Obesity is the leading cause of preventable death in the world. According to actuarial charts, body mass index is the most accurate predictor of life span. The excess food it takes to make the normal person obese uses a lot of oxygen for processing. Says Wenk: "First fat ages you, then it kills you."
Once excess calories are turned into fat and stored, fat cells release cytokines, little proteins sent out by the immune system to destroy such interlopers as bacteria. They attack by causing inflammation, which eradicates the foreign bodies. Like much warfare, however, there's collateral damage; neighboring cells are caught in the cross fire. In the brain, inflammation abets dementia—so much so that arthritis sufferers, who typically down lots of anti-inflammatory drugs, tend to bypass dementia.
Taking megadoses of anti-inflammatory drugs has its own risks: gastrointestinal bleeding. Far safer to decrease the size of your belly. A recent report fingered the foods that most lead to long-term weight gain: French fries, potato chips, sugary drinks, red meat, and processed meats such as hot dogs. Eaten regularly, they cause obesity, upping the risk of high cholesterol levels, type 2 diabetes, and dementia.