Figure 1.

The number of Alzheimer's disease (AD) cases that could potentially be prevented through risk factor reductions of 10% or 25% worldwide (Figure 1a) and in the US (Figure 1b) was estimated by multiplying current prevalence estimates by 0.90 and 0.75, respectively, and subtracting the revised number of attributable cases from the original number. These estimates assume that a causal relationship exists between the risk factor and AD and that the relative risk estimate is a good approximation of the impact of risk factor reduction. Therefore, the actual number of cases prevented could be higher or lower depending on the extent to which these assumptions are valid. In addition, the combined estimate assumes that the individual risk factors are independent and have an additive relationship. Because several of the risk factors examined are inter-related, the combined PAR estimates should be considered as maximums.