Trends in modifiable risk factors for dementia among midlife adults in the United States: The National Health and nutrition examination survey 1999-2018.

Objective: Dementia has a large public health burden, and modifiable risk factors, particularly in midlife, may provide an opportunity for early prevention. We aimed to examine trends in age-adjusted prevalence of modifiable risk factors for dementia and the number of modifiable risk factors among midlife adults from 1999 to 2018.

Methods: A total of 14,851 participants aged 40 to 64 years without a history of cardiovascular disease in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were included in the analysis. The age-adjusted prevalence of six modifiable risk factors consistently measured across all surveys, including hypertension, diabetes, hyperlipidemia, obesity, smoking, and heavy drinking, as well as the average number of these modifiable risk factors, were estimated and compared across survey periods. Subgroup analyses were conducted by sex, race/ethnicity, education, and family income.

Results: The age-adjusted prevalence of diabetes (p for linear trend <0.0001) and obesity (p for linear trend = 0.0001) showed increasing trends from 1999 to 2018 among midlife adults in the U.S. and in virtually all subgroups, while smoking showed a decreasing trend (p for linear trend <0.0001). The average number of modifiable risk factors remained around two (p for linear trend = 0.84).

Conclusion: The prevalence of diabetes and obesity increased in this large, nationally representative U.S. study population, while the prevalence of smoking decreased. More effective public health interventions are needed to mitigate the impact of these risk factors and ultimately reduce the burden of dementia in aging populations.