The Enigma of Decreasing Dementia Incidence

The incidence of dementia increases with advancing age. 1 In association with increasing life expectancy, the absolute number of persons with dementia has been increasing worldwide.In the face of that statistic, the article by Tom et al 2 in JAMA Network Open reports a slight reduction in dementia incidence rates among persons born after 1929 compared with those born earlier.Multiple investigations in Europe and the US 1,3 have made similar observations.The consistency of the finding across multiple epidemiological cohorts, although not universal, raises the question of how such a favorable but unexpected trend developed.While it is not possible to exclude variations in diagnostic approaches over time, it is worth considering which advances in health care delivery or sociocultural trends could be associated with a decreasing rate of incident dementia.