Impact of interventions to reduce Alzheimer's disease pathology on the prevalence of dementia in the oldest-old.

INTRODUCTION: The number of persons aged >90 years will grow significantly in coming decades. This group has the highest rates of dementia, most commonly Alzheimer's disease (AD). METHODS: Using The 90+ Study, we developed a statistical model for dementia risk based on brain pathologies. Intervention scenarios which reduce or eliminate AD pathology were considered, and the numbers of dementia cases among the U.S. oldest-old that could be prevented were estimated. RESULTS: The U.S. dementia prevalence among the oldest-old will increase from 1.35 million in 2015 to 4.72 million in 2050. If interventions eliminate AD pathology, dementia prevalence would be reduced by approximately 50%, averting nearly 2.4 million cases in 2050. However, large numbers of dementia cases would still remain. DISCUSSION: Reducing AD pathology would significantly decrease the public health burden of dementia. However, other interventions are needed to address the burden associated with other dementing pathologies prevalent in the oldest-old.