A modest proposal for a longitudinal study of dementia prevention (with apologies to Jonathan Swift, 1729).

Many studies have documented the role of risk and protective factors for late life dementing illnesses, particularly Alzheimer's disease. A "Systematic Review" from the US Agency for Healthcare Research and Quality and the National Institute on Aging concluded that because the overall quality of evidence was low, recommendations for public health could not be made. In order to gain evidence for the efficacy of lifestyle interventions, we propose a "Modest Proposal" to study 10,000 subjects over 40 years randomly assigned to groups of low or high saturated fat in the diet, head injury, and high or low levels of mental activity, physical activity, or inactivity as well as smoking or non-smoking. This proposed study cannot be accomplished. The "Modest Proposal" illustrates that the absence of definitive evidence should not restrict physicians from making reasonable recommendations based on the evidence that is available.