The National Institutes of Health delivered a disturbingly negative message this week to those who worry about Alzheimer's disease -- a message that many found too downbeat, and criticized for failing to emphasize some important, if only mildly hopeful, points.
Following a large study, the NIH panel concluded that none of the methods used in attempts to prevent, delay or reduce the severity of Alzheimer's disease have been proven to work. Specifically, mental stimulation, exercise, and a variety of diets and dietary supplements accomplish nothing.
"Alzheimer's disease is a feared and heart-breaking disease," said Dr. Martha L. Daviglus, the panel's chairwoman and professor of preventive medicine and geriatric medicine at Northwestern University in Chicago. "We wish we could tell people that taking a pill or doing a puzzle every day would prevent this terrible disease, but current evidence doesn't support this."
No Evidence to Support Alzheimer's Prevention
Alzheimer's disease is a progressive, incurable and fatal brain disease affecting some 5.3 million Americans. The degenerative condition destroys brain cells, causing memory loss and problems with thinking and behavior severe enough to affect all aspects of life. Alzheimer's disease and other dementias cost more than $148 billion in the U.S. annually and exact a significant toll -- financial, physical and mental -- from caregivers.
The disease has proven challenging for scientific research, in part due to an incomplete understanding of the disease, the panel said. And as conventional medicine has supplied little relief, many have turned to other therapeutic regimens, believing that following a healthy lifestyle and keeping the brain active might reduce their Alzheimer's risk.
No such thing, says the NIH panel. Even vitamin E, often prescribed by doctors, was found to make no statistical difference in Alzheimer's risk. Another popular supplement, ginkgo bilboa was likewise found to make no difference in cognitive progression. The rest of the associations were founded on weak studies and evidence.
Factors with Weak Association
Factors found to be associated with an increased risk of developing Alzheimer's include diabetes, a number of cardiovascular risk factors (elevated blood cholesterol in midlife and high blood pressure), depression, smoking, loss of a spouse or never being married, and having a limited social support system. But those findings are all supported by very weak data.
Conversely, those factors found to be mildly associated with a reduced risk of Alzheimer's disease were also supported by very weak evidence. They include:
Adequate levels of folic acid;
Adhering to a diet low in saturated fats and high in fruits and vegetables -- though a recent study found that such a Mediterranean diet indeed lowers the risk of Alzheimer's;
Use of statins -- a recent study found no relation;
Light to moderate consumption of alcohol;
More years of education;
Higher levels of mental engagement;
Physical activity and a range of leisure activities (e.g., club membership, religious services, painting, gardening).
And as Dr. Daviglus noted, "An association only tells us that these things are related, not that one causes the other."
Did anything look like it might help? "The most consistent evidence is available for the longer chain omega-3 fatty acids (often measured as fish consumption)." But just last week, even that was thrown into doubt after a randomized, placebo-controlled trial of nearly 900 septuagenarians found that omega-3 fatty acid supplements had no effect on cognition.
Panel Failed to Emphasize Value of Healthy Lifestyle, Diet
The panel's conclusions are quite pessimistic, but they follow the science. If publicizing those results can protect people from snake oil sellers, then the more widely they can be made known, the better. On the other hand, the importance of a healthy lifestyle and a proper diet is underestimated in the report, likely due to the context.
Yet, with the panel's findings that heart disease, high blood pressure and diabetes are associated with increased Alzheimer's risk, and with evidence that a healthy lifestyle and diet can affect these conditions, a note emphasizing their importance may have been warranted.
Today, Alzheimer's disease is the seventh-leading cause of death in the U.S., and the most common form of dementia. According to the Alzheimer's Association, African-Americans and Hispanics are at higher risk for developing the condition.