The foods we choose make a difference.
Alzheimer’s Disease
In my clinical practice, the one diagnosis I dreaded giving more than cancer was Alzheimer’s. It wasn’t just because of the psychological toll to come for the patient but because of the emotional toll that would be placed on loved ones. The Alzheimer’s Foundation estimates that fifteen million friends and family members supply more than fifteen billion unpaid hours annually caring for loved ones who may not even recognize them.59
Despite the billions of dollars spent on research, there is still neither a cure nor an effective treatment for the disease, which invariably progresses to death. In short, Alzheimer’s is reaching a state of crisis—emotionally, economically, and even scientifically. Over the past two decades, more than seventy-three thousand research articles have been published on the disease. That’s about a hundred papers a day. Yet very little clinical progress has been made in treating or even understanding it. And a total cure is likely impossible, given that lost cognitive function in Alzheimer’s patients may never be regained due to fatally damaged neuronal networks. Dead nerve cells cannot be brought back to life. Even if drug companies can figure out how to halt the disease’s progression, for many patients, the damage has already been done, and the individual’s personality may be forever lost.60
The good news, as a senior scientist at the Center for Alzheimer’s Research entitled a review article, is that “Alzheimer’s Disease Is Incurable but Preventable.”61 Diet and lifestyle changes could potentially prevent millions of cases a year.62 How? There is an emerging consensus that “what is good for our hearts is also good for our heads,”63 because clogging of the arteries inside of the brain with atherosclerotic plaque is thought to play a pivotal role in the development of Alzheimer’s disease.64 It is not surprising, then, that the dietary centerpiece of the 2014 “Dietary and Lifestyle Guidelines for the Prevention of Alzheimer’s Disease,” published in the journal Neurobiology of Aging, was: “Vegetables, legumes (beans, peas, and lentils), fruits, and whole grains should replace meats and dairy products as primary staples of the diet.”65
Is Alzheimer’s a Vascular Disorder?
In 1901, a woman named Auguste was taken to an insane asylum in Frankfurt, Germany, by her husband. She was described as a delusional, forgetful, disoriented woman who “could not carry out her homemaking duties.”66 She was seen by a Dr. Alzheimer and was to become the subject of the case that made Alzheimer a household name.
On autopsy, Alzheimer described the plaques and tangles in her brain that would go on to characterize the disease. But lost in the excitement of discovering a new disease, a clue may have been overlooked. He wrote, “Die größeren Hirngefäße sind arteriosklerotisch verändert,” which translates to “The larger cerebral vessels show arteriosclerotic change.” He was describing the hardening of arteries inside his patient’s brain.67
We generally think of atherosclerosis as a condition of the heart, but it’s been described as “an omnipresent pathology that involves virtually the entire human organism.”68 You have blood vessels in every one of your organs, including your brain. The concept of “cardiogenic dementia,” first proposed in the 1970s, suggested that because the aging brain is highly sensitive to a lack of oxygen, lack of adequate blood flow may lead to cognitive decline.69 Today, we have a substantial body of evidence strongly associating atherosclerotic arteries with Alzheimer’s disease.70
Autopsies have shown repeatedly that Alzheimer’s patients tend to have significantly more atherosclerotic plaque buildup and narrowing of the arteries within the brain.71,72,73 Normal resting cerebral blood flow—the amount of blood circulating to the brain—is typically about a quart per minute. Starting in adulthood, people appear to naturally lose about half a percent of blood flow per year. By age sixty-five, this circulating capacity could be down by as much as 20 percent.74 While such a drop alone may not be sufficient to impair brain function, it can put you close to the edge. The clogging of the arteries inside, and leading to, the brain with cholesterol-filled plaque can drastically reduce the amount of blood—and therefore oxygen—your brain receives. Supporting this theory, autopsies have demonstrated that Alzheimer’s patients had particularly significant arterial blockage in the arteries leading to the memory centers of their brains.75 In light of such findings, some experts have even suggested that Alzheimer’s be reclassified as a vascular disorder.76
There are limitations to how much we can glean from autopsy studies, however. For example, perhaps a person’s dementia led to his or her poor diet rather than vice versa. To further assess the role of clogged brain arteries in the development of Alzheimer’s, researchers followed about four hundred people who were just starting to lose their mental faculties, which is called mild cognitive impairment. Special brain-artery scans were employed to evaluate the amount of arterial blockage in each patient’s brain. The researchers found that the cognition and daily functioning of those with the least narrowing of the arteries in their heads remained stable over the course of the four-year study. Meanwhile, subjects with more arterial blockage lost significant brain function, and those with the worst cases of plaque buildup declined rapidly, doubling their likelihood of progressing to full-blown Alzheimer’s. The researchers concluded: “An inefficient blood supply to the brain has very grave consequences on brain function.”77
A study of three hundred Alzheimer’s patients found that treating vascular risk factors, such as high cholesterol and blood pressure, may even slow the progression of the disease but not stop it.78 That’s why prevention is the key. Cholesterol doesn’t just help generate atherosclerotic plaques within your brain arteries; it may help seed the amyloid plaques that riddle the brain tissue of Alzheimer’s victims.79 Cholesterol is a vital component of your cells, which is why your body makes all that you need. Consuming excess cholesterol, and especially trans and saturated fats, can raise your blood cholesterol level.80 Too much cholesterol in your blood is not only considered the primary risk factor for heart disease81 but is also unanimously recognized as a risk factor for Alzheimer’s disease.82
Autopsies have revealed that Alzheimer’s brains have significantly more cholesterol buildup than normal brains.83 We used to think that the pool of cholesterol in the brain was separate from the cholesterol circulating in the blood, but there is growing evidence to the contrary.84 Excess cholesterol in the blood can lead to excess cholesterol in the brain, which may then help trigger the clumping of amyloid seen in Alzheimer’s brains. Under an electron microscope, we can see the clustering of amyloid fibres on and around tiny crystals of cholesterol.85 And indeed, advanced brain imaging techniques, such as PET scans, have shown a direct correlation between the amount of LDL (“bad”) cholesterol in the blood and amyloid buildup in the brain.86 Drug companies have hoped to capitalize on this connection to sell cholesterol-lowering statin drugs to prevent Alzheimer’s, but statins themselves can cause cognitive impairment, including short- and long-term memory loss.87 For people unwilling to change their diets, the benefits of statins outweigh the risks,88 but it’s better to lower your cholesterol levels naturally by eating healthier to help preserve your heart, brain, and mind.
Genetics or Diet?
This dietary concept may be surprising, because most of the popular press today treats Alzheimer’s as a genetic disease. They say it’s your genes, rather than your lifestyle choices, that determine whether or not you’ll succumb. However, when you examine the distribution of Alzheimer’s disease around the world, that argument begins to crumble.
The rates of Alzheimer’s vary tenfold around the world, even taking into account that some populations live longer than others.89 For example, in rural Pennsylvania, if you knew one hundred senior citizens, it is likely that an average of nineteen of them would develop Alzheimer’s disease within the next decade. However, that number would probably be closer to just three out of one hundred if you lived in rural Ballabgarh, in India.90 How do we know some populat
ions aren’t just more genetically susceptible? Because of migration studies, in which disease rates within the same ethnic group are compared between their current locale and their homeland. For example, the Alzheimer’s rates among Japanese men living in the United States are significantly higher than those of Japanese men living in Japan.91 The Alzheimer’s rates among Africans in Nigeria are up to four times lower than those of African Americans in Indianapolis.92
Why does living in the United States increase dementia risk?
The balance of evidence suggests that the answer lies in the American diet. Of course, in our new global world, you don’t have to move to the West to adopt a Western diet. In Japan, the prevalence of Alzheimer’s has shot up over the past few decades, thought to be due to the shift from a traditional rice-and-vegetable-based diet to one featuring triple the dairy and six times the meat. The closest correlation researchers found between diet and dementia was animal fat consumption; animal fat intake shot up nearly 600 percent between 1961 and 2008.93 A similar trend linking diet and dementia was found in China.94 With diets Westernizing globally, Alzheimer’s rates are expected to continue to increase, writes one researcher in the Journal of Alzheimer’s Disease, “unless dietary patterns change to those with less reliance on animal products. . . .”95
The lowest validated rates of Alzheimer’s disease in the world are found in rural India,96 where people eat traditional, plant-based diets centered on grains and vegetables.97 In the United States, those who don’t eat meat (including poultry and fish) appear to cut their risk of developing dementia in half. And the longer meat is avoided, the lower dementia risk may fall. Compared to those eating meat more than four times a week, those who have eaten vegetarian diets for thirty years or more had three times lower risk of becoming demented.98
Surely genetic factors play some part? They do. Back in the 1990s, scientists discovered a gene variant called apolipoprotein E4, or ApoE4, that makes you more susceptible to getting Alzheimer’s. Everyone has some form of ApoE, but about one in seven people have a copy of the E4 gene that is linked to the disease. It’s been shown that if you inherit one ApoE4 gene from your mother or father, your risk of getting Alzheimer’s may triple. If you get the ApoE4 gene from both parents—which about one in fifty people do—you might end up with nine times the risk.99
What does the ApoE gene do? It makes the protein that’s the principal cholesterol carrier in the brain.100 The E4 variant may lead to an abnormal accumulation of cholesterol within brain cells, which could trigger Alzheimer’s pathology.101 This mechanism may explain the so-called Nigerian paradox. The highest frequency of the ApoE4 variant occurs in Nigerians,102 who surprisingly also have some of the lowest rates of Alzheimer’s.103 Wait a second. The population with the highest rate of the “Alzheimer’s gene” has one of the lowest rates of Alzheimer’s disease? This contradiction may be explained by Nigerians’ extremely low blood-cholesterol levels, thanks to a diet low in animal fat104 and consisting mainly of grains and vegetables.105 So, it seems, diet can trump genetics.
Consider that in one study of a thousand people over a period of two decades, the presence of the ApoE4 gene, unsurprisingly, was found to more than double the odds of Alzheimer’s. But in those same subjects, high blood cholesterol was found to nearly triple the odds. The researchers suspect that controlling such risk factors as high blood pressure and cholesterol could substantially reduce the risk of Alzheimer’s, dropping the odds from up around ninefold with the dreaded, double-barreled ApoE4 down to just twice the risk.106
Too often, doctors and patients have a fatalistic approach to chronic degenerative diseases, and Alzheimer’s is no exception.107 “It’s all in your genes,” they say, “and what will happen will happen.” Research shows that although you might have been dealt some poor genetic cards, you may be able to reshuffle the deck with diet.
Preventing Alzheimer’s with Plant Foods
Alzheimer’s manifests as a disease of the elderly, but like heart disease and most cancers, it’s a disease that may take decades to develop. At the risk of sounding like a broken record (or should I say an MP3 glitch?), it’s never too early to start eating healthier. Dietary decisions you make now may directly influence your health much later in life, including the health of your brain.
Most Alzheimer’s sufferers aren’t diagnosed until they’re in their seventies,108 but we now know that their brains began deteriorating long before that. Based on thousands of autopsies, pathologists seemed to detect the first silent stages of Alzheimer’s disease—what appear to be tangles in the brain—in half of people by age fifty and even 10 percent of those in their twenties.109 The good news is that the clinical manifestation of Alzheimer’s disease—like heart disease, lung disease, and stroke—may be preventable.
Plant-based diets are recommended in Alzheimer’s prevention guidelines because of which foods they tend to accentuate and which they tend to reduce.110 The Mediterranean diet, for example, which is higher in vegetables, beans, fruits, and nuts, and lower in meats and dairy products, has been associated with slower cognitive decline and lower risk of Alzheimer’s.111 When researchers tried to tease out the protective components, the critical ingredients appeared to be the diet’s high vegetable content and lower ratio of saturated to unsaturated fats.112 This conclusion aligns with that of the Harvard Women’s Health Study, which found that higher saturated fat intake (sourced predominantly from dairy, meat, and processed foods) was associated with a significantly worse trajectory of cognition and memory. Women with the highest saturated fat intake had a 60–70 percent greater chance of cognitive deterioration over time. Women with the lowest saturated fat intake had the brain function, on average, of women six years younger.113
The benefits of a plant-based diet may also be due to the plants themselves. Whole plant foods contain thousands of compounds with antioxidant properties,114 some of which can traverse the blood-brain barrier and may provide neuroprotective effects115 by defending against free radicals (see here)—that is, protecting against the “rusting” of the brain. Your brain is only about 2 percent of your body weight but may consume up to 50 percent of the oxygen you breathe, potentially releasing a firestorm of free radicals.116 Special antioxidant pigments in berries117 and dark-green leafies118 may make them the brain foods of the fruit and vegetable kingdom.
The first human study to show that blueberries improve memory abilities in older adults exhibiting early cognitive deterioration was published in 2010.119 Then, in 2012, Harvard University researchers actually quantified these findings by using data from the Nurses’ Health Study, in which the diets and health of sixteen thousand women were followed starting in 1980. They found that women who consumed at least one serving of blueberries and two servings of strawberries each week had slower rates of cognitive decline—by as much as two and a half years—compared with those who didn’t eat berries. These results suggest that simply eating a handful of berries every day, one easy and delicious dietary tweak, may slow your brain’s aging by more than two years.120
Even just drinking fruit and vegetable juices may be beneficial. A study that followed nearly two thousand people for about eight years found that people who drank fruit and vegetable juices regularly appeared to have a 76 percent lower risk of developing Alzheimer’s disease. “Fruit and vegetable juices may play an important role in delaying the onset of Alzheimer’s disease,” the researchers concluded, “particularly among those who are at high risk for the disease.”121
The researchers suspect the active ingredient may be a class of powerful brain-accessing antioxidants called polyphenols. If that’s the case, Concord (purple) grape juice may be the best choice,122 although whole fruits are generally preferable to juices.123 Concord grapes aren’t always in season, though, so look for cranberries, which are also packed with polyphenols124 and can typically be found frozen year-round. (Later in this book, I offer my Pink Juice recipe for a whole-food cranberry cocktail with twenty-five times fewer calories
and at least eight times the phytonutrient content of shop-bought cranberry “juice.” See here.)
Beyond their antioxidant activity, polyphenols have been shown to protect nerve cells in vitro by inhibiting the formation of the plaques125and tangles126 that characterize Alzheimer’s brain pathology. In theory, they could also “pull out”127 metals that accumulate in certain brain areas and may play a role in the development of Alzheimer’s and other neurodegenerative diseases.128 Polyphenols are one of the reasons I make specific recommendations for berries and green tea in part 2.
Treating Alzheimer’s with Saffron
Despite the billions poured into Alzheimer’s research, there is no effective treatment to reverse the progression of the disease. There are medications that can help manage the symptoms, though, and so can something found right in your supermarket.
Although some remarkable benefits have been reported in anecdotal case studies with the spice turmeric,129 the best data we have on spice-based interventions for Alzheimer’s is for saffron. A spice derived from the flower of Crocus sativus, saffron was found in a double-blind trial to help diminish the symptoms of Alzheimer’s disease. In a sixteen-week study, Alzheimer’s patients with mild to moderate dementia who took saffron capsules displayed significantly better cognitive function on average than a group of patients who took a placebo.130
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