Although there is considerable debate among scientists on both the importance and thegenerality of different aging mechanisms, in recent years three interrelated perspectives ofaging have emerged on which most gerontologists and demographers agree: (1) there aremultiple pathways (and thus mechanisms) for attaining exceptional longevity; (2) thesepathways have different mortality consequences; and (3) the health of individuals at older agesis conditional on their pathway to these ages. The concept of pathways to old age and theirdifferent health costs is foundational to healthy aging outlined in the landmark paper onmorbidity compression by Fries (1980) and is also central to this proposed project. One of thefundamental questions that flows from these concepts is whether increasing survival ofindividuals to advanced ages yields populations that are healthier, or whether these largerfractions arriving at old age means that the average health of the individuals is actually reduced.Whereas this second scenario is referred to as the 'Failure of Success Model', the first scenariois referred to as the 'Success of Success Model'. A less selected group of survivors to old agesmay be shaping an older population whole health profile is more diverse relative to earlierpopulations at the same age. These concepts and models will be used to form the operationalframework around which this proposed research project is organized to explore the interplay ofgeriatric and demography frailty and, in turn, to gain insights into the relationship of health andold-age mortality. Using the Mexican fruit fly (Anastrepha ludens), our broad goal is to bringexperimental demography and mathematical models to bear on specific questions concernedwith the health and survival of older individuals that experience a wide range of environmentalconditions when young.
Specific aims i nclude:
Aim 1. Identify and calibrate behavioral metrics ofhealth;
Aim 2. Health metric measurement and hypothesis testing including assessing health,survival and female reproduction of oldest-old flies maintained different diets (2a) and differentreproductive (2b) and stress (2c) conditions;
and Aim 3. Statistical modeling and data analysis.
One of the fundamental questions in the demography of aging is whether increasing survival of individuals to an advanced age yields populations that are healthier or whether these larger fractions arriving at old age means that the average health of the individuals is actually reduced. The proposed research will provide answers to these questions by measuring health and survival at older ages in flies that were subject to qualitatively and quantitatively-different environments (i.e. pathways) when they were young. The studies will be among the first to answer these questions systematically through carefully controlled studies using a fruit fly model system.
| Su, Yu-Ru; Wang, Jane-Ling (2016) SEMIPARAMETRIC EFFICIENT ESTIMATION FOR SHARED-FRAILTY MODELS WITH DOUBLY-CENSORED CLUSTERED DATA. Ann Stat 44:1298-1331 |
