The way we age depends on a mixture of intrinsic and extrinsic forces. Extrinsic factors such as healthy habits can be controlled. However, a significant portion of aging is determined by genes, which may encode causative factors involved in aging or factors that delay aging and/or promote extended health span (longevity assurance factors). In humans, it has been estimated that genetics control 25 to 40 percent of life and health span variability, but the identity of the responsible genes is difficult to pinpoint. Basic researchers have identified about 100 genes that control lifespan in model organisms, including roundworms called nematodes, yeast, fruit flies, and mice. Further research is needed to understand the relationships among these genes and to determine whether or not the equivalent genes in humans function in a similar fashion. Research has also identified subtle and reversible changes in human genes, which, in some cases, can be passed from generation to generation and can control the level of activity of some genes. These “epigenetic” changes represent another area of research that might yield further insights into aging and age-related disease.
Scientists supported by NIA are particularly interested in identifying genetic factors that contribute to healthy aging as well as unraveling the genetic and biological processes involved in age-related traits and diseases. Our hope is that the discovery and increased understanding of genes involved in aging and longevity will lead to the development of medical and behavioral interventions that can slow the aging process and, most importantly, delay or prevent the onset of age-associated diseases.