What to Eat to Reduce Your Risk of Alzheimer's Disease, According to Science
Susan Avery seemed more at home in the supermarket than a box of cereal. Wielding a coffee in one hand and a menu she printed at home in the other, she rolled her shopping cart over to the bakery, hunting for the perfect whole-grain loaf. She spotted a man wearing a black Wegmans cap and solicited his help. "Sir? Do you have any other than just this one whole-wheat?"
Avery was being picky because she's on a diet. Not a diet to lose weight, but a diet to nourish her brain. As a professor at Ithaca College in New York, Avery, 62, is especially keen to keep her mind sharp, yet recently she has had trouble remembering words. In the grocery store a few moments later, I watched as she fumbled to recall that the large packages of beans she likes are called family packs. Avery's aunt suffered from Alzheimer's disease, the devastating condition that currently afflicts 5.4 million Americans, robbing them of their memory and cognition. Avery wants to avoid that fate. Right now, Alzheimer's has no cure: doctors have run more than 500 clinical trials on potential drugs, but none has prevented the disease or significantly slowed its course. And the Centers for Disease Control and Prevention estimates that by 2050, 14 million Americans will suffer from it.
So when Avery came across the U.S. News & World Report diet rankings last summer and discovered that the No. 2 Best Overall Diet, the MIND diet, was supposed to be especially good for the brain, she decided to give it a shot. "It just made sense to me," says Avery. She's been following the diet ever since. She invited me to join her that day to introduce me to the diet.
I'm near 40 and my grandmother had Alzheimer's. She died when I was young, but I recall that my grandfather became her full-time caregiver. By the end, Alzheimer's patients like my grandmother lose not only their memory, but also their ability to care for themselves. So there I was with Avery—watching her pile multigrain bread, wild-caught salmon, spinach, broccoli, squash and mushrooms into her shopping cart. My mission: to understand more about how the MIND diet feeds her brain.
Some might call Avery crazy for thinking that a diet could stave off Alzheimer's. A large part of the medical community scoffs at the idea that something as simple as diet could fend off this debilitating disease. But a growing body of research stands in the face of popular opinion. Much of this research came from the lab of Martha Clare Morris, Sc.D., a former nutritional epidemiologist at Rush University Medical Center in Chicago who passed away in 2020. She's spent decades researching how food influences cognition and used her discoveries to create the MIND diet. MIND stands for Mediterranean-DASH Intervention for Neurodegenerative Delay. It is based on the Mediterranean diet and the DASH diet (Dietary Approaches to Stop Hypertension), but it focuses on foods that have been specifically shown to boost brain health. Morris found that people who eat more of certain foods—red meat, sweets, saturated fats—are more likely to develop Alzheimer's, while people who load up on berries, fish, whole grains, nuts, beans, olive oil and—perhaps most important—leafy green vegetables, such as spinach, kale and broccoli, tend to stay healthy. In two studies published in 2015, Morris and her colleagues reported that older adults who closely follow this eating pattern are less likely to develop Alzheimer's disease, plus they score better on cognitive tests than those who don't.
Yet Morris said the MIND diet is not just for older people. Alzheimer's disease can take decades to develop—a 2013 study reported that the signature amyloid plaques begin to accumulate in the brain 20 years—two decades—before symptoms start. Even people who are not destined to get Alzheimer's are still at risk for age-related cognitive decline, which can start to take root as early as age 30. We don't always know where our brains are headed, but what we eat throughout our lives may shape their final destination.
Food for Thought
Morris has been investigating the idea of a brain-focused diet for decades. After she earned her doctorate in epidemiology at the Harvard School of Public Health and ran an important aging study in Iowa, Rush University Medical Center in Morris's hometown, Chicago, recruited her to lead a study teasing out the various lifestyle factors—including foods—that might protect against Alzheimer's disease. "At the time, there was no nutrition research on neurodegenerative diseases like Alzheimer's, so I thought I had to study it," said Morris.
This was a monster of a study. "We sent a team of census takers to every house and apartment in three South Side Chicago communities," she explained to me one especially cold, snowy morning in December over a coffee (no cream or sugar). They ended up following nearly 4,000 healthy older adults for 20 years, interviewing them every three years to understand their lifestyle habits and giving some of them neurological tests.
Over time, analyzing their own findings and those from other researchers, Morris and her colleagues teased out which foods seemed brain-healthy and which were not. They then created a list of 15 (10 "good" foods and 5 "bad") and analyzed the eating habits of their study participants with a focus on these foods. Eating good foods earned participants MIND points and eating bad foods detracted from their scores. Then, in a litmus test, they compared the diet scores to how well each participant did on neurological tests over time. The results were inspiring: people with the highest MIND scores were indeed less likely to develop Alzheimer's disease (53 percent less likely, in fact) than people with the lowest diet scores. And on cognitive tests, they performed as if they were 7½ years younger.
The best foods to eat were: whole grains, leafy greens, berries, nuts, beans, vegetables, wine, fish, poultry and olive oil. The ones to reduce were: red meat, fried and fast food, whole-fat cheese, butter/margarine and sweets. (Learn more about the best MIND diet foods to eat and the foods to avoid for brain health.)
Historical examples back up Morris's findings linking nutrients to brain health. In the 1980s and '90s, researchers discovered that babies' brains grow most rapidly when flooded with an omega-3 fatty acid called DHA, and that human breast milk contains plenty of this nutrient. Doctors have long known, too, that the adult brain doesn't run properly without the right nutrients. Vitamin B12 deficiencies cause memory loss and confusion; too little niacin gives rise to dementia and depression. Through food, we fuel all of our organs—we are what we eat, right?—and the brain is especially hungry, because it is constantly toiling.
Building the Case
Still, it's one thing to say that the brain requires certain nutrients and quite another to claim that nutrition can prevent a disease like Alzheimer's. After all, Alzheimer's has a strong genetic component: genetic mutations can directly incite early-onset cases that afflict people under 60. But what many might not know is that most of the time, a blend of genetic and lifestyle factors causes Alzheimer's. When Morris gave genetic tests to the individuals in her studies, she found that among those who had gene mutations known to increase Alzheimer's risk, the MIND diet was less protective, but it still made a difference.
And if you consider what happens to the brain when the disease takes hold, the ties to nutrition become clearer. Over time, the brain gets severely damaged by inflammation as well as by oxidative stress. These processes disrupt cell function and lead to the buildup of plaques and tangles. Once the cells become very injured, they die, and as the cell death spreads, Alzheimer's sets in.
The thing about inflammation and oxidative stress is that certain nutrients can potentially mitigate them, both in the brain and in the rest of the body. And some others, such as saturated fat and sugar, can ramp up the body's production of compounds that incite inflammation. (Here are the best foods to eat to fight inflammation.)
To better understand the connection between genes and lifestyle, I spoke with Trish Whitaker, a 66-year-old former schoolteacher living in Conway, Arkansas. "I'm from the South—from the land where they roll it in sugar and butter and then fry it," she explained to me in a soft Arkansas accent. Whitaker knows how strong the genetic connection to Alzheimer's can be. Both of her parents, as well as both of her sisters, developed the disease. But an October 2015 meeting with Richard Isaacson, M.D.—a neurologist who directs the Alzheimer's Prevention Clinic at Weill Cornell Medicine and NewYork-Presbyterian in Manhattan—inspired Whitaker to become much more careful about what she ate. It was Whitaker's daughter who discovered Isaacson. She came across his book, The Alzheimer's Diet—which has similar recommendations to Morris's on the types of foods that could stave off Alzheimer's—and encouraged her mom to read it. Whitaker was so intrigued she drove 1,300 miles to see Isaacson in person.
"Now my favorite is spinach sautéed in olive oil," Whitaker says. Research suggests this dish likely calms inflammation in her body and brain. Lab studies have shown that a compound in olive oil called oleocanthol behaves a lot like the anti-inflammatory drug ibuprofen, suppressing the activity of two well-known inflammatory enzymes in the body called COX-1 and COX-2. Extracts from spinach have been shown to tamp down those harmful enzymes too.
Oxidative stress is the other damaging process associated with Alzheimer's that can build up throughout the body and wreak havoc. All day our cells use nutrients to make energy, releasing tiny, powerful molecules (free radicals) as waste, causing damage to cells. But free radicals are neutralized by molecules called antioxidants. Foods like leafy greens and berries happen to be very rich in antioxidants, so when we eat them, we provide our bodies with greater means to reduce oxidative stress. One class of antioxidants called flavonoids, found in blueberries and strawberries, have been shown in animal studies to protect vulnerable neurons and help neurons regenerate. The antioxidant vitamin E (good sources include almonds, spinach and sunflower seeds) sits on the outer layer of brain cells "to snatch up free radical molecules right when they occur so that they can't harm the cell," Morris said.
Related: Best Antioxidant-Rich Foods
There's an interesting story to tell about sugar when it comes to the brain too. In the 1980s, researchers discovered that insulin, the hormone made by the pancreas that regulates blood sugar levels, can cross the blood-brain barrier. Although brain insulin doesn't have the same sugar-controlling job, it plays a role in learning and memory. These findings piqued the interest of Suzanne de la Monte, M.D., a neurosurgeon and pathologist at Brown University, who decided in 2005 to compare brain insulin levels in healthy people and those with Alzheimer's. She found that brain processes involving insulin are severely impaired in Alzheimer's, which led her to start calling Alzheimer's "Type 3 Diabetes." This, of course, implicates diets because a sugar-rich diet interferes with insulin signaling and sensitivity throughout the body. In fact, people with type 2 diabetes, a disease characterized by reduced insulin sensitivity, are more than twice as likely to develop Alzheimer's.
Morris, Isaacson and de la Monte's work isn't the only research to have linked diet to brain health. Several studies have reported that the Mediterranean diet is associated with a lower risk of dementia too. In a study published in January 2017, researchers in the UK and Canada reported that people in their 70s who followed a Mediterranean-style diet lost less brain volume over a three-year period than people who did not. In a 2013 study, Spanish researchers put 522 middle-aged-to-older adults on either a Mediterranean diet or a low-fat diet for 6½ years. Subjects following the Mediterranean diet fared much better on cognitive tests at the end of the trial. And a review of 12 studies, published in 2013, concluded that greater adherence to the Mediterranean diet is associated with slower cognitive decline and lower risk of developing Alzheimer's disease.
You might think that the Alzheimer's and neurology scientific communities would be thrilled by this new bounty of research—finally, a potential way to reduce the toll of Alzheimer's. Mostly, though, they're still doubtful. "I get made fun of," Isaacson says. "One colleague called me the 'blueberry neurologist.'" Morris told a similar story: "The field of neurology is very skeptical that diet might influence diseases of the brain." When I reached out to the moderator of an Alzheimer's support group on Facebook, whose members include Alzheimer's patients and caregivers, hoping to post a question about diet, I was told not to bother: "Most members don't believe that diet will help."
Why is this idea so controversial? One problem is that many neurologists aren't trained in nutrition, so they don't consider it as potentially important in the development of brain diseases. "I got maybe four hours' worth of nutrition education in my neurology training," Isaacson says, which frustrated him so much he took the initiative to take additional nutrition coursework. And even when neurologists have heard that nutrition could play a role in dementia, they don't always know just how much research has accumulated to support the idea. When Isaacson gets pushback from doctors who scoff at the idea, he replies with: "Guess what? There is evidence, and let's talk about it."
Certainly, the field could stand to have more clinical trials—which are better at establishing cause-and-effect than the types of observational studies Morris has been conducting. Fortunately, Morris won a $14.5 million grant in April 2016 from the National Institute on Aging to conduct the world's first MIND diet clinical trial, which will run in Chicago and Boston for three years. The trial will test whether following the MIND diet improves cognition among 600 overweight people who generally eat poorly. If the trial establishes evidence that the diet helps them, it will be possible to test whether it helps healthier people as well. At Weill Cornell, Isaacson is monitoring how various dietary and lifestyle changes relate to future cognitive outcomes.
A Mindful Meal
When we arrived back at Susan Avery's house after grocery shopping, she took a bottle of chardonnay from the fridge. "It's 5 o'clock somewhere," she announced. (Really, it was 4:30.) The MIND diet recommends one glass of wine a day. Her husband, Doug, who follows MIND with her, was joining us for dinner. He admitted that he'd stopped for fast food on the way home from a lunchtime doctor's appointment. The good news, though, is that even just partially following the diet may have cognitive benefits. Morris's study found that people whose MIND diet scores were in the middle range—6.5 to 8.5 points out of a maximum of 15—were still 35 percent less likely to develop Alzheimer's compared with people with the lowest MIND diet scores.
Over our wine, Avery and I talked about how her life has changed on the MIND diet. She used to choose meals primarily on taste and convenience; pasta and red meat were staples. The MIND diet is more work for her in terms of meal planning and shopping—she has a Post-it note stuck to her car's glove compartment to remind her what to eat and what to avoid. And the food preparation involved is a change for her too. After 90 minutes of chopping, sautéing, roasting and baking, she brought dinner to the table.
The colorful feast—baked Dijon-glazed salmon, sautéed spinach with garlic, roasted vegetables and mushroom farro—was delicious and it felt good to eat a meal that was designed to fuel my brain. We may not yet know exactly how protective the MIND diet is, but with my family history of Alzheimer's and the harsh reality of no cure, I decided then and there that I, too, was going to make some changes—more berries and fish, less sugar and refined carbs. One thing Morris said to me in Chicago stuck with me: "The longer you have healthy lifestyle practices, the more long-term benefit you have."
Over dessert of baked pears, I asked Avery whether she has noticed any cognitive changes since starting the diet four months ago. "Maybe I am forgetting less now, but I think that's almost too simplistic," she says. She can't be sure if the food is truly making a difference or if her expectations are muddying her perspective. Whitaker, who made her dietary changes over a year ago, is more confident. She feels she hasn't had as many forgetful moments as she used to. "Before I went to Dr. Isaacson, anytime I would forget anything, I would say, 'Is Alzheimer's here? Is this the beginning?' I rarely ever say that anymore," she says. "If nothing else, making these changes has reduced my fear quite a bit. Maybe it's because it's given me a measure of control over my life. I am doing something. Every day, I'm doing things to keep my brain healthy."
It's not just about food—other lifestyle choices might make a difference too.
Regular exercise could both reduce the risk of Alzheimer's in healthy adults and boost cognitive performance among people with minor memory loss. A 2014 review of 22 trials found that regular exercise, such as walking and tai chi, boosts cognition among adults with mild cognitive impairment. This could be because, as recent research suggests, physical activity sparks the growth of new neurons and blood vessels inside the brain and boosts brain blood flow. A 2011 study also found that among older adults, regular exercise increases the size of the hippocampus, the region of the brain responsible for memory that gets damaged early on in Alzheimer's. (Check out the best exercises for women over 50.)
Keeping your brain engaged is important too. In a 2014 study, researchers discovered that people who had more than eight years of schooling were half as likely to be diagnosed with Alzheimer's as people who received less than that. These findings suggest that learning and mental stimulation build a kind of "cognitive reserve" that protects the brain in as yet unknown ways. Another large study found that the risk of Alzheimer's disease was 47 percent lower among adults who did mentally engaging things like read the newspaper, visit museums and attempt puzzles every day compared to people who did these kinds of activities once a year or less. Can't find time every day? Don't sweat it: even participants who did these activities more often than once a year, but not daily, lowered their risk of Alzheimer's.
Melinda Wenner Moyer is a science and parenting journalist based in New York's Hudson Valley. She is a regular contributor to Scientific American.
This article originally appeared in the May 2017 Issue of EatingWell Magazine