The fight to prevent age-related cognitive decline and Alzheimer’s disease has spurred sales of crossword puzzles and other brainteasers, put fish oil supplements on Americans’ shopping lists and opened new avenues of physical activity and social engagement for seniors.
But while mental stimulation, exercise and a host of dietary supplements have been studied over the years, there is insufficient evidence to support that these or any other strategies for delaying the onset of Alzheimer’s disease or reducing its severity are effective, according to an independent panel of experts convened by the National Institutes of Health in April.
“Alzheimer’s disease is a feared and heartbreaking disease,” said Martha L. Daviglus, MD, PhD, MPH, conference panel chair and professor of preventive 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.”
Progress to understand how the onset of the disease might be delayed or prevented is limited by inconsistent definitions of what constitutes Alzheimer’s disease and cognitive decline, the panel found. Other factors include incomplete understanding of the natural history of the disease and limited understanding of the aging process in general. The panel recommended that the research community and clinicians collaborate to develop, test and uniformly adopt objective measures of baseline cognitive function and changes over time.
In a draft consensus statement released in April, the panel noted no evidence “of even moderate scientific quality” supporting the association of dietary supplements, the use of prescription or nonprescription drugs, diet, exercise and social engagement with reduced risk of Alzheimer’s disease. The evidence for reducing cognitive decine is similarly limited, the panel said. Although many risk factors have been examined, age is the strongest known risk factor for Alzheimer’s disease, according to the panel. However, improved understanding of genetic risk factors may ultimately lead to effective therapies.
Additionally, 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, the panel found. 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.
Cognitive decline and Alzheimer’s disease are major sources of morbidity and mortality worldwide, posing a significant burden not only on affected individuals, but also on their caregivers and society in general, the panel said.
According to the National Institute on Aging, as many as 2.4 million to 5.1 million Americans have Alzheimer’s disease, and unless the disease can be effectively treated or prevented, the number of people with the disease will increase significantly. According to NIA, the number of people ages 65 and older is expected to grow to 72 million in 2030 — up from 39 million in 2008 — and the number of people with Alzheimer’s disease doubles for every five-year interval.
“Extensive research over the past 20 years has provided important insights on the nature of Alzheimer’s disease and cognitive decline and the magnitude of the problem,” the panel concluded. “Nevertheless, there remain important and formidable challenges in conducting research on these diseases, particularly in the area of prevention.”
The panel pointed to numerous ongoing or planned investigations which may offer promising new insights regarding the causes and prevention of these diseases.
To view the panel’s draft consensus statement, “Preventing Alzheimer’s Disease and Cognitive Decline,” visit www.consensus.nih.gov/2010/alzstatement.htm.
- Copyright The Nation’s Health, American Public Health Association
