In light of recent research that indicates promising new diagnostic technology that could enable physicians to accurately diagnose Alzheimer's disease years before the patient is even exhibiting symptoms, the National Institutes of Health commissioned a comprehensive study to determine what can be done to prevent the disease at its State-of-the-Science Conference, held August 26th-August 28th.
A group of independent researchers convened to examine the currently available scientific evidence on Alzheimer's disease, associated risk factors and possible preventative measures. Analyzing data from scientific studies conducted on human sample populations in developed countries, with a sample size of at least 50, researchers concluded that no convincing scientific evidence exists to support that any modifiable factor can reduce the risk of developing Alzheimer's disease. Modifiable factors include vitamins, herbal supplements, social and economic factors, enivronmental expsoures, prescription and non-prescription drugs, and other dietary and lifestyle factors.
While there are numerous studies that reveal a correlation between a dietary or lifestyle factor and risk of Alzheimer's disease, the panel states that the overall scientific quality of these studies is low. A positive association also does not indicate that any factor studied is the cause of a lower or higher risk of developing Alzheimer's disease.
Of course, the current lack of a consistent definition of Alzheimer's disease makes analyzing the current body of research challenging. It's also difficult to differentiate between a factor that is associated with Alzheimer's disease or whether the relationship is actually with older age. In other words, many factors that have been implicated with an increased risk of Alzheimer's disease are much more prevalent with age, and age is a known risk factor for Alzheimer's disease -- so any factor associated with aging could be subsequently implicated as an Alzheimer's risk factor.
Among the few consistent findings, this meta-analysis revealed the following about associations between various factors and general cognitive decline, which is a different measure than Alzheimer's disease:
- There is consistent evidence from several longitudinal studies that omega-3 fatty acids (found in fish) are associated with a reduced risk.
- Depression and related symptoms have been associated with mild cognitive impairment and cognitive decline.
- The loss of a spouse has a strong association with cognitive decline.
- Some positive associations have been found with physical and leisure activities (club memberships, gardening, painting) and preservation of cognitive function.