Paleolithic Nutrition: Alzheimer’s and Diet

Caring for husband with dementia. Image: iStockphotoAmericans over the age of 65 have a one in a million chance of winning the lottery, and a one in eight chance of developing Alzheimer’s.

Dr. John
Lecture: New Research on the Role of Nutrition in Neurological Function

By John Michael

There are currently 5.4 million people with Alzheimer’s disease in the United States, and “barring medical breakthroughs,” by 2050 that number is projected to grow to as much as sixteen million. According to the Alzheimer’s Association’s 2011 Facts and Figures, “between 2000 and 2025, some states and regions across the country are expected to experience double-digit percentage increases in the overall number of people with Alzheimer’s.” Nor is the United States alone in experiencing an increase in this disease. A recent study reported a growth in the number of cases in Beijing, and in Britain the Prince of Wales last year warned of a coming epidemic. 

This surge is attributed to the growing elderly populations in both developed and developing countries. As deaths from other causes like heart disease decrease, the number of deaths attributable to Alzheimer’s, and especially Alzheimer’s-related pneumonia, are increasing. And even when it doesn’t kill those it afflicts, Alzheimer’s often significantly reduces life expectancy, with “61 percent of people with Alzheimer’s at age 70 […] expected to die before age 80 compared with 30 percent of people at age 70 without Alzheimer’s.”

Alzheimer’s disease is a common form of dementia, accounting for between sixty to eighty percent of all cases. It develops slowly, appearing as memory and mood problems, like forgetfulness, apathy, and depression. Over months and years, the disease progresses, causing “impaired judgment, disorientation, confusion, behavior changes, and difficulty speaking, swallowing, and walking.” The person affected by Alzheimer’s is gradually rendered helpless by this disease. Those who can afford to become reliant upon the care of trained professionals, while those who cannot must rely on the assistance of family members and other unpaid caregivers.

Though the greatest factor in the development of Alzheimer’s is advancing age, it is a disease, and “not a normal part of aging.” The risk of developing Alzheimer’s is generally agreed to be augmented by multiple factors, among them poor cardiovascular health, the presence of diabetes and hypertension, physical inactivity, and smoking and obesity.

Unfortunately, the precise cause of Alzheimer’s remains unknown. While researchers understand more and more about the mechanism by which this disease operates, no effective treatment exists to cure it.

The hallmarks of the disease, revealed in post-mortem autopsies, are the plaques and tangles that damage the brains of Alzheimer’s sufferers. Plaques are deposits of the protein beta-amyloid that gather upon brain cells, while tangles are accumulations of the protein tau, which collect within the cells themselves. New science suggests that beta-amyloid is produced in the liver of Alzheimer’s sufferers, and that it gathers upon brain cells after having been brought there by the cardiovascular system. One study found that beta-amyloid strips insulin receptors from neurons, thus increasing resistance to insulin, which is necessary for the formation of memories. This finding has led to speculation that Alzheimer’s could be a third type of diabetes. Another study, reported in the New York Times, found that the progression of Alzheimer’s was slowed by nasally administering doses of insulin to those suffering from it.

But perhaps most interesting is the research suggesting that diet can play a powerful role in the prevention of this disease. In the study “Nutrition and Alzheimer’s Disease: The Detrimental Role of a High-Carbohydrate Diet,” the authors begin by stating that “an excess of dietary carbohydrates, particularly fructose, alongside a relative deficiency in dietary fats and cholesterol, may lead to the development of Alzheimer’s disease.” They then assert that eating too many carbohydrates “leads to a cholesterol deficiency in neurons, which significantly impairs their ability to function.”

From a Paleo perspective, the modern American diet can aggravate many of our contemporary ailments, including Alzheimer’s. While evidence to support this suspicion is still not definitive, there is ethnographic research noting the absence of senile dementia in traditional societies that avoid industrial foods. The Kitava Study observed the health of the inhabitants of the remote Melanesian island of Kitava, “one of the last populations on Earth with dietary habits matching what would have been the case for the population of Homo sapiens in their original habitats.” The Kitavans eat a unique Paleo diet that is 95% vegan, consisting mostly of vegetables and tubers, and which is supplemented by fish. Senile dementia is completely unknown in Kitavan society; not only was none discovered by researchers, but no Kitavan surveyed could recall having witnessed a case. This absence of Alzheimer’s in traditional societies is echoed by Dr. Hugh Trowell, a British physician who managed a psychiatric ward in Nairobi during the colonial period, and who reported that among the disorders affecting his patients “senile dementia was a notable absentee.

While dietary modification is probably a good way to reduce the risk of developing Alzheimer’s, until stronger evidence appears in its favor, it should be regarded as a preventative measure, and not a guaranteed method of avoiding this disease.

(Unless otherwise noted, all information cited in this blog came from the Alzheimer’s Association’s 2011 Facts and Figures.)