Key result
Age-specific dementia incidence declines by up to ~20% per decade over the past 30 years.
Why the study?
The factors underlying changing temporal trends in dementia incidence are not entirely clear, despite observed declines in age-specific dementia incidence over recent decades.
Educational attainment in the United States has increased steadily since 1940, which is discussed in the context of the declining incidence of dementia.
Provides context for the declining incidence of dementia; leaves open whether this population-level trend directly modifies individual.
As people are living longer, the disease burden is shifting toward diseases of old age, including an increasing prevalence of dementia, most commonly because of Alzheimer disease (AD). The risk of developing dementia doubles every 5 years after the age of 65 years.1 There are currently 5.1 million Americans aged >65 years living with dementia, and this number is expected to reach 13.8 million by the year 2050.2 Despite an increasing prevalence of dementia, the FHS (Framingham Heart Study) recently showed that the age-specific incidence of dementia has steadily declined over the previous 3 decades (Figure).3 In other words, whereas the overall number of people affected by dementia will continue to increase because of population aging, an individual’s risk of developing dementia by a specific age has decreased by as much as 20% each decade over the past 30 years. Other studies have also pointed toward a declining incidence of dementia in the United States and Europe.4–6 The Health and Retirement Study also reported a decline in dementia prevalence in the United States from the year 2000 to 2012.7 Collectively, these studies provide hope that some cases of dementia can be prevented or delayed. Figure. Trends in ( A ) dementia incidence and ( B ) education and vascular risk factors over four nonoverlapping epochs in the Framingham Heart Study. The baseline examination period was from 1977 to 1983 for the first epoch, 1986 to 1991 for the second epoch, 1992 to 1998 for the third epoch, and 2004 to 2008 for the fourth epoch. Data are from Satizabal et al.3 BP indicates blood pressure; HDL-C, high-density lipoprotein cholesterol; high school, completion of high-school education; and Rx, treatment. The factors underlying changing temporal trends in dementia are not entirely clear. It is important to understand what …
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Pase et al. (2017) conducted an editorial in Dementia. Improved vascular health was evaluated. The age-specific incidence of dementia has steadily declined, with an individual's risk of developing dementia by a specific age decreasing by as much as 20% each decade over the past 30 years.
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