The incidence of dementia is declining throughout the developed world.1,2 The decline is unexpected and also underappreciated, transpiring against the trend of population aging, so that even as age-adjusted incidence of dementia is decreasing, the number of individuals developing dementia annually continues to increase, imposing enormous societal burden. Understanding the sources for this decline and using that understanding to improve care are important goals for patients, physicians, and policy makers. The decline in dementia has been ascribed to various potential causes, including improved control of cardiovascular risk factors, better education, increased wealth, and greater use of anti-inflammatory drugs.1,2 Two articles in this issue of JAMA provide salient insights.3,4