Risk of developing Alzheimer's disease is increased by older age, genetic factors, and several medical risk factors. Studies have also suggested that dietary and lifestyle factors may influence risk, raising the possibility that preventive strategies may be effective. This body of research is incomplete. However, because the most scientifically supported lifestyle factors for Alzheimer's disease are known factors for cardiovascular diseases and diabetes, it is reasonable to provide preliminary guidance to help individuals who wish to reduce their risk. At the International Conference on Nutrition and the Brain, Washington, DC, July 19–20, 2013, speakers were asked to comment on possible guidelines for Alzheimer's disease prevention, with an aim of developing a set of practical, albeit preliminary, steps to be recommended to members of the public. From this discussion, 7 guidelines emerged related to healthful diet and exercise habits.
Alzheimer's disease affected an estimated 4.7 million Americans in 2010, and its prevalence is expected to nearly triple in coming decades (Hebert et al., 2013). Several factors contribute to the risk of developing late-onset Alzheimer's disease, including older age, genetic factors (especially the presence of the APOEε4 allele), family history, a history of head trauma, midlife hypertension, obesity, diabetes, and hypercholesterolemia (Bendlin et al., 2010).
In addition, recent prospective studies have shown that certain dietary and lifestyle factors, including saturated fat intake, vitamin E intake, and physical exercise, among others, are associated with Alzheimer's risk, suggesting that prevention strategies may be applicable for these factors. In each of these areas, scientific evidence is less than complete. Nonetheless, individuals at risk for Alzheimer's disease make decisions about dietary and lifestyle on a daily basis and need to act on the best evidence available to them, even when scientific consensus may not have been achieved.
In toxicology, the “precautionary principle” is invoked in situations in which there is a substantial basis for concern regarding the health consequences of an exposure and for which available data preclude a comprehensive evaluation of risk (European Commission, 2000). A similar approach can be applied to nutritional and other lifestyle-related exposures, particularly for conditions, such as cancer or Alzheimer's disease, for which there may be a long latency period between exposure and disease manifestation and for which randomized controlled trials are impractical or are, for whatever reason, not rapidly forthcoming. Some have argued that the level of evidence required for making dietary recommendations for disease prevention may be different from that required for establishing the efficacy of medical treatments, such as pharmaceuticals (Blumberg et al., 2010).
At the International Conference on Nutrition and the Brain, Washington, DC, July 19–20, 2013, evidence regarding the influence of dietary factors, physical and mental exercise, and sleep on aspects of cognition was reviewed, and conference speakers were asked to comment on possible dietary and lifestyle guidelines for Alzheimer's disease prevention, with an aim of developing a set of practical steps to be recommended to members of the public.
Although current scientific evidence is incomplete, substantial evidence suggests that, a combination of healthful diet steps and regular physical exercise may reduce the risk of developing Alzheimer's disease. These lifestyle changes present additional benefits, particularly for body weight, cardiovascular health, and diabetes risk, and essentially no risk of harm. As investigations into Alzheimer's disease bear additional fruit, these guidelines should be modified accordingly.
