Her fears were soon validated: A battery of tests, including one for a gene that essentially guarantees Alzheimer's, confirmed her suspicions. She wasn't shocked; at least five of her father's siblings died with Alzheimer's symptoms. Two of her siblings have it, and her 47-year-old daughter is already beginning to show signs.
"I feel very blessed I'm still in the early stage," says Marquez, now 69 and living in Seattle. After her diagnosis, she charged into what she calls "warrior mode," campaigning to raise awareness of Alzheimer's while also working to stave off her own decline. Step one: Overhaul her "junky" diet. Instead of pasta, pizza, and fast food, she now eats Mediterranean style, loading up on veggies; focusing on chicken, fish, and tofu for protein; and limiting refined sugars and grains.
Dietary changes may seem inconsequential in the face of a diagnosis as monstrous as Alzheimer's, but there's reason to believe they're crucial. At a lab at Wake Forest School of Medicine, Suzanne Craft, a professor of gerontology and geriatric medicine, is studying how what we eat affects our brains and, in the process, revolutionizing the way we think about preventing and treating dementia.
Alzheimer's is the most common form of dementia, and the National Institutes of Health's National Institute on Aging estimates that it's the sixth-leading cause of death in the United States. It often runs in families, but fewer than 5% of Alzheimer's cases are directly caused by a genetic variation such as the one Marquez carries. There's usually no way to tell who will get it—in part because no one really knows what causes it.
Related: 5 Surprising Alzheimer's Triggers
Today, most Alzheimer's research is based on the hypothesis that symptoms are triggered by abnormal deposits of proteins in the brain called amyloid plaques and tau tangles. With no confirmed cause and no effective long-term treatments for the disease, researchers have turned to other factors that might be at play. It's likely, says Laurie Ryan, chief of the Dementia of Aging Branch of the National Institute on Aging's division of neuroscience, that Alzheimer's does its damage via multiple pathways.
One of those pathways seems to involve type 2 diabetes. People who have it are at least twice as likely to develop Alzheimer's as those who don't—an association so strong that in 2005, a neuropathologist named Suzanne de la Monte suggested that Alzheimer's could be referred to as "type 3 diabetes." That term, while controversial, has gained traction among some scientists as a way to focus attention on why the diseases often coexist.
Whatever you call it, the connection is worth exploring: Nearly 30 million Americans have diabetes, and 40% of people born today are expected to develop the disease in their lifetimes. If we want to protect America's mental health, we'd better figure out what the link is. Fast.
Ann Simpson is a vivacious woman with a cheerful smile and an easy laugh. Ask her about Alzheimer's, though, and she quickly grows serious. "It's a nasty, nasty disease," she says quietly.
Simpson, 69, has already lost her mother and one sister to the disease; another sister has developed it as well. The sister living with Alzheimer's no longer remembers Ann's name or what money is. She ripped up a photo of a dear grandchild. "It's devastating," Simpson says, "and I'm scared to death that I may get it."
Given her family history—her deceased sister had both Alzheimer's and type 2 diabetes—Simpson was a perfect fit for a study, led by Craft, focusing on the role of insulin. Craft believes that much of the connection between Alzheimer's disease and type 2 diabetes has to do with this hormone.
Secreted in response to food, insulin removes sugar (glucose) from your blood and moves it into your cells, where it's used for energy. But sometimes the body doesn't use insulin as efficiently as it should. This is called insulin resistance, which means your body needs to release more insulin than normal to respond to the same amount of glucose. That might work for a while, but it's like using a leaky bucket to put out a fire: Because your body can pump out excess insulin for only so long, you'll eventually end up with chronically elevated blood sugar levels. That's type 2 diabetes.
The disease is well known for the havoc it wreaks on the body, but Craft and a growing number of researchers are more interested in what type 2 diabetes does to the brain. They're also exploring the role of insulin and blood sugar levels on memory in people who don't have diabetes—at least not yet. And the No. 1 factor that affects your blood sugar levels, and thus determines how much insulin you need, is your intake of carbohydrates.
Related: 7 Reasons Why You're Forgetful That Have Nothing To Do With Alzheimer's
The idea that there's a connection between diet and health may sound like old news, but Craft has gone beyond traditional observational studies.
"I'm an experimentalist by nature," she says, "and I wanted to do a very tightly controlled diet study to see whether we could affect people's cognition and the Alzheimer's markers in their spinal fluid by giving them a 'Western' diet high in sugar and saturated fat for 30 days."
That's exactly what she did. She took 49 older adults, 29 of whom had early signs of Alzheimer's disease and 20 of whom did not, and randomly assigned them to one of two diets. The first, high in saturated fat and easily digested carbohydrates, was meant to mimic the stereotypical American diet. The second was more Mediterranean, with less saturated fat and a focus on complex carbs (like whole grains and legumes) that take a longer time to be absorbed and therefore don't cause the same spike in insulin as simple carbs do.
By the end of the month, the people who had been assigned to the Western-style diet performed worse on memory tests than they had at the beginning of the trial, and Alzheimer's-related beta-amyloid proteins showed up in their spinal fluid. Those who'd been assigned to the Mediterranean-style diet, on the other hand, did better on the tests, and their spinal fluid contained fewer Alzheimer's-related proteins. The effects reversed once participants returned to their normal eating patterns at the end of the study.
In a different trial, Craft found that people's cognitive abilities temporarily decreased—and that beta-amyloid in their spinal fluid temporarily increased—following a single high-carb meal. "It's surprising to see changes in these markers after just one meal," says Ryan.
Related: What It's Like To Have A Spouse With Alzheimer's
The question is, how does this happen?
When Craft started her research on Alzheimer's some 20 years ago, "the idea that there was an important connection between insulin and the brain—let alone insulin and Alzheimer's—was viewed as so novel as to be fringe," she says. Instead, researchers were focused on glucose. At the time, neurologists knew that the brains of people with Alzheimer's disease didn't use glucose properly. So Craft designed a small trial that tested whether giving people a boost of glucose via a sugary beverage could temporarily improve their performance on a cognitive test.
She was happy to find that it did. But it wasn't for the reason she had expected.
When the release of insulin was blocked, the memory benefit vanished. "The transient benefit to memory was tied not to the glucose but to elevations in insulin that happen naturally when people are given glucose," Craft says.
Scientists still don't understand why. But they do know that insulin is essential to the hippocampus, a seahorse-shaped structure in which our memories are created. Without adequate insulin, the hippocampus can't access the energy it needs to do its job—and memories can't be recorded efficiently. Insulin also acts as a neurotransmitter, a chemical that enables brain cells to communicate with each other. It modulates the levels of other brain chemicals that interact with memory. It also reduces inflammation, directs blood flow, and helps repair and create brain cells.
It might seem, therefore, that having extra insulin circulating in your body would be good for your mind. But that's not the case. When insulin levels in the body are abnormally high, the brain protects itself by restricting how much insulin it can absorb. In the short term, this shields the brain from the fluctuations in insulin levels that occur after meals. But when insulin levels are consistently elevated, as they are when you're insulin resistant, this process backfires and an insufficient amount of insulin reaches the brain. Ironically, the more insulin there is circulating in the bloodstream, the more likely it is that your brain isn't getting enough of it.
Craft isn't ready to say that less insulin in the brain actually causes Alzheimer's disease, in part because Alzheimer's is a highly specific term. Usually diagnosed after death, it means a person had the classic plaques and tangles as well as memory symptoms. And not everyone with age-related memory changes has Alzheimer's. "What we're studying is really the role of insulin in Alzheimer's symptoms," Craft says.
Craft and her team are now wrapping up a larger version of their original diet trial. She's also running a study she believes will prove that an ultra-low-carb diet is superior to the low-fat diet recommended by the American Heart Association when it comes to preserving brain health.
So far, Craft's findings offer a possible rationale for why a diet high in processed carbs (which promote insulin resistance) and type 2 diabetes (characterized by insulin resistance) increases the risk of Alzheimer's disease. They provide a plausible explanation for why several recent observational studies have found an association between a relatively low-carb, Mediterranean-inspired eating pattern called the MIND diet and a lower risk of Alzheimer's. Most important, they suggest that each of us can take steps to reduce our risk of developing Alzheimer's, starting with our next meal.
Like any responsible scientist, Craft has caveats. Her studies are ongoing, and she doesn't yet know how powerful the effects of dietary patterns on Alzheimer's risk may be. There is no question, however, that diet can affect our minds, she says—and that the typical American diet doesn't appear to be healthy.
Related: 9 Ways To Control Your Risk Of Alzheimer's
Other researchers are also cautiously optimistic. While these are preliminary findings, says Martha Clare Morris, a professor of nutritional epidemiology at Rush University Medical Center who studies the role of diet in preventing chronic diseases like Alzheimer's, it's now an "aggressively studied" area of research, as scientists and hopeful families alike clamor for a cure.
"People need to recognize that everything they put in their mouths has an impact on their brains," Craft explains. "Eating poorly and depriving your brain is absolutely going to affect how it functions over time."
She knows that some people will be skeptical. "Patients say to me, 'I ate well and exercised my whole life, and I'm 80 and I have Alzheimer's,'" Craft says. "What I say to them is that if you hadn't done that, you might have gotten Alzheimer's at 60."
Her advice: Eat a Mediterranean-style diet featuring lots of produce and fatty fish. Avoid refined grains and processed foods. Exercise. ("Diet and exercise work synergistically," Craft says.) Basically, do everything in your power to avoid becoming insulin resistant.
"How diet works in the brain is complicated, but what to do is not," Craft says. "To a large extent, the health of our brains is under our control."
This article was originally published by our partners at Prevention.