Panel finds inconclusive evidence that diet, exercise, supplements prevent dementia
MONDAY, June 14 (HealthDay News) -- There is not enough evidence to say that improving your lifestyle can protect you against Alzheimer's disease, a new review finds.
A group put together by the U.S. National Institutes of Health looked at 165 studies to see if lifestyle, diet, medical factors or medications, socioeconomic status, behavioral factors, environmental factors and genetics might help prevent the mind-robbing condition.
Although biological, behavioral, social and environmental factors may contribute to the delay or prevention of cognitive decline, the review authors couldn't draw any firm conclusions about an association between modifiable risk factors and cognitive decline or Alzheimer's disease.
However, one expert doesn't belive the report represents all that is known about Alzheimer's.
"I found the report to be overly pessimistic and sometimes mistaken in their conclusions, which are largely drawn from epidemiology, which is almost always inherently inconclusive," said Greg M. Cole, associate director of the Alzheimer's Center at the University of California, Los Angeles.
The real problem is that everything scientists know suggests that intervention needs to occur before cognitive deficits begin to show themselves, Cole noted. Unfortunately, there aren't enough clinical trials underway to find definitive answers before aging Baby Boomers will begin to be ravaged by the disease, he added.
"This implies interventions that will take five to seven years or more to complete and cost around $50 million. That is pretty expensive, and not a good timeline for trial-and-error work. Not if we want to beat the clock on the Baby Boomer time bomb," he said.
The report is published in the June 15 online issue of the Annals of Internal Medicine.
The panel, chaired by Dr. Martha L. Daviglus, a professor of preventive medicine at the Feinberg School of Medicine at Northwestern University, found that although lifestyle factors -- such as eating a Mediterranean diet, consuming omega-3 fatty acids, being physically active and engaging in leisure activities -- were associated with a lower risk of cognitive decline, the current evidence is "too weak to justify strongly recommending them to patients."
In addition, while factors such as the gene marker APOEe4, the metabolic syndrome (which includes risk factors such as obesity, high cholesterol and high blood pressure), and depression were associated with a higher risk of cognitive decline, again the evidence was not convincing, the panel found.
Moreover, "there is insufficient evidence to support the use of pharmaceutical agents or dietary supplements to prevent cognitive decline or Alzheimer's disease," the panel wrote.
There was strong evidence that smokers or people with diabetes do have an increased risk for cognitive decline, they noted.
Dr. Sam Gandy, associate director of the Alzheimer's Disease Research Center at Mount Sinai School of Medicine in New York City, agreed that to really settle the question of whether lifestyle has an impact on dementia, clinical trials need to be conducted.
"The next steps will be randomized clinical trials of the items that are most tractable to study: physical exercise, mental exercise, diet, to see whether we can prove that our epidemiological leads can be validated using the 'gold standard' clinical trial paradigm," he said.
The panel did note that there is a lot of promising research on medication, diet, exercise and keeping mentally active as ways of slowing or preventing cognitive decline.
"What you do to stop from getting the disease may vary with the nature of your risk," Cole said. "This is common sense but not always built into the thinking of clinical trial design. These are some of the things that we need to change. Otherwise, we may end up with more or less the same expert panel report 10 years from now."
Another expert, Maria Carrillo, senior director of medical and scientific relations at the Alzheimer's Association, believes the study lays out an agenda for what is needed to build evidence for preventing Alzheimer's disease.
"But we are not going to be able to fulfill that agenda if we don't have the increases in federal funding in order to get that done," she said. "We know that without treatments this disease is going to bankrupt our economy. So we need to back up that agenda with the dollars."
Alzheimer's disease comprises 60 percent to 80 percent of all dementia cases, and may affect as many as 5.1 million Americans. The number of people with mild cognitive impairment is even larger, the review authors added.
For more information on Alzheimer's disease, visit the Alzheimer's Association .
SOURCES: Sam Gandy, M.D., Ph.D., professor, neurology and psychiatry, and associate director, Alzheimer's Disease Research Center, Mount Sinai School of Medicine, New York City; Greg M. Cole, Ph.D., professor, medicine and neurology, and associate director, Alzheimer's Center, University of California, Los Angeles; Maria Carrillo, Ph.D., senior director, medical and scientific relations, Alzheimer's Association; June 15, 2010, Annals of Internal Medicine, online
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