Predictors of Age at Onset of Dementia among Oldest Old Americans

Background: Higher prevalence of Alzheimer's disease and other dementias in the U.S. population imposes a substantial burden on the country's health care system The primary objective of this study is to examine role of socioeconomic and lifestyle related factors across lifespan on the age at onset of dementia, including Alzheimer's disease (AD) in the U.S. population. Method: The Aging Demographics and Memory Study (ADAMS) data were used to examine factors associated with the age of onset of AD and other dementia. The ADAMS is a cross-sectional supplemental sample of individuals age 70 or older selected from the Health and Retirement Study. The age at onset of dementia was estimated if respondents meet DSM criteria based on review of the chronological history of cognitive and functional symptoms. A list of lifestyle, socioeconomic, and health related factors including birth year, education, physical exercise, and childhood socioeconomic status was regressed on the outcome variable of onset age of dementia. Results: An earlier year of birth, being women, having stroke , and Apolipoprotein-E4 gene were associated with lower onset age, while regular exercise, being Hispanic have positive impact on delaying the age of onset. Low paternal education had a significant impact on the earlier age of dementia onset. Conclusion: Modifiable lifestyle factors can delay the onset of dementia.Americans with less educated fathers have the lower age of onset. Public health impact of delaying the onset is tremendous as it would lower the prevalence rate and consequently social and economic burdens of the disease.