Print“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 rigorous studies have shown that any means used to prevent or delay the onset of Alzheimer’s or reduce the impairment to mental abilities caused by the disease actually work, according to a National Institutes of Health panel. The experts looked at a variety of strategies use to protect against the disease and its effects including mental stimulation, exercise, and a variety of dietary supplements.
“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,” says Martha L. Daviglus, professor of preventive medicine and medicine at Northwestern University, Chicago and chair of the panel.
The 15-member panel, convened at an NIH Consensus Development Program conference, found that efforts to understand how people might protect themselves against the disease or its effects is limited by inconsistent definitions of what constitutes Alzheimer's disease and cognitive decline. Other limiting factors, the panel said, include incomplete understanding of the natural history of the disease and limited understanding of the aging process in general. The panel said the research community and clinicians need to collaborate to develop, test, and uniformly adopt objective measures of baseline cognitive function and changes over time.
The panel determined that there is currently no evidence of even moderate scientific quality supporting the association of any modifiable factor-dietary supplement intake, use of prescription or non-prescription drugs, diet, exercise, and social engagement-with reduced risk of Alzheimer's disease. The evidence surrounding risk reduction for cognitive decline is similarly limited. Low-grade evidence shows weak associations between many lifestyle choices and reduced risk of Alzheimer's disease and cognitive decline.
“These associations are examples of the classic chicken or the egg quandary. Are people able to stay mentally sharp over time because they are physically active and socially engaged or are they simply more likely to stay physically active and socially engaged because they are mentally sharp?” says Daviglus. “An association only tells us that these things are related, not that one causes the other."
Age remains the strongest known risk factor for Alzheimer's disease. There is also strong evidence that a genetic variant of a cholesterol-ferrying protein (apolipoprotein E) confers increased risk. Although it is hoped that improved understanding of genetic risk factors may ultimately lead to effective therapies, currently these associations are primarily useful in the clinical research setting.
The panel found that certain chronic diseases, such as diabetes and depression, and risk factors such as smoking are associated with increased risk of both Alzheimer's disease and cognitive decline. However, studies have not yet demonstrated that these medical or lifestyle factors actually cause or prevent Alzheimer's disease or cognitive decline, only that they are related. The panel said there is insufficient evidence to support the use of pharmaceuticals or dietary supplements to prevent Alzheimer's disease or cognitive decline.
The panel made a variety of recommendations to shape the future research agenda and fill identified gaps, while acknowledging that advancing the understanding of these complex conditions in order to develop conclusive, evidence-based prevention recommendations will require considerable time and resources. Those recommendations include launching long-term, longitudinal studies to better characterize the natural history and progression of these diseases in the community. They also recommended the establishment of registries for Alzheimer's disease and cognitive decline, modeled on existing registries for cancer.
April 30, 2010
http://www.burrillreport.com/article-alzheimer%e2%80%99s_quandary.html
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