Numerous studies have documented a role for inherited genetic variation in common chronic diseases, their risk factors and overall longevity. However, the distributions and incidence rates of these same conditions have changed dramatically during modern times (1946-2014); a shift too dramatic in too short of a period to be affected by evolutionary pressures leading to changes in allele frequencies. Rather, this shift is most likely accounted for by changes in health care and lifestyle, which, in turn, have led to increased longevity and opening the door to successful aging. Lifestyle changes and aging itself can lead to alterations in the action of relevant genes via epigenetic modification of the DNA. This proposed research will test the hypotheses that signatures of DNA methylation measured in the blood of middle-aged adults are associated with successful aging patterns later in life (Aim 1); that these signatures persist in old age (Aim 2); and these signatures are associated with subsequent differences in the expression level of relevant genes (Aim 3). Replication opportunities have been identified and are an integral part of the workscope. We will focus on the overall construct of successful aging (i.e., physical, cognitive and functional well-being) instead of any one disease entity or risk factor for both scientific (i.e., pleiotropy) and practical (impact on quality of life) reasons. We will use the Level II definition of successful aging proposed and validated by McLaughlin et al in the Health and Retirement Study. The Atherosclerosis Risk in Communities (ARIC) Study, a biracial longitudinal cohort study of the development of atherosclerosis and its risk factors, has collected and stored biosamples at each of its previous five examinations, and measured blood biomarkers and DNA sequence variation in successful searches for predictors of disease risk. This proposed ancillary study will support measurement of epigenetic patterns associated with successful aging. The following specific aims will be pursued: 1) To identify signatures of DNA methylation measured in the blood of middle-aged adults that are associated with successful aging status later in life; 2) To determine whether DNA methylation signatures of successful aging established in middle age among 1,800 ARIC participants from Aim 1 persist ~21 years later when they reach old age; 3) To examine whether the DNA methylation status of the genes identified in middle age (Aim 1) is correlated with gene expression in old age. The long-term goal of the proposed project is that by increasing our understanding of the biological determinants and trajectory of successful aging, this study may help to inform public health interventions focused on modifiable risk factors and the development of new therapeutic agents that will make successful aging an attainable goal for a greater number of individuals in the population.
Numerous studies have documented a role for inherited genetic variation in common chronic diseases such as cardiovascular disease and diabetes, their risk factors and overall longevity. However, the gain in nearly 30 years of life expectancy over the last century in the United States and other developed countries, driven in part by reductions in mortality among the elderly, has resulted in changes in disease prevalence that cannot be accounted for by alterations in allele frequency during the same period. This suggests the need to better understand how genes are influenced by the environment without changing the DNA sequence (epigenetics). To increase our knowledge of the biological determinants of the aging process and ultimately to contribute to the design of targeted public health interventions, a study of locus-specific DNA methylation in blood will be carried out in the biracial Atherosclerosis Risk in Communities (ARIC) study to test the hypothesis that methylation signatures established in middle age are associated with the overall construct of successful aging (i.e., physical, cognitive, and functional well-being) assessed over 20 years later, and that the midlife successful aging pattern of methylation persists in those that successfully age.
