In this application, we propose to initiate a data archive comprising the National Academy of Sciences-National Research Council World War II Twin Registry (NAS-NRC Twin Registry) in order to make this unique resource available to the scientific community. We apply Tom Brokaw's label "The Greatest Generation" to describe the men in this registry. Thus, while this is a study of veterans, it is actually a study of a cohort over its adult lifetime. This context makes the preservation of the registry more vital, as it is representative of a generation. This application encompasses the first stages of the complete proposed archiving project. The twin registry includes 15,924 white male twin pairs born 1917-1927 in which both members of the pair were in the military. Data currently available at the Medical Follow-up Agency (MFUA) at the National Academies include abstracted service records, medical diagnoses from the period of service through 1984, 40 years of mailed epidemiological questionnaires beginning in the 1960s, education, occupation, earnings, family composition, leisure activities, and personality. For at least 4800 individuals, there are [Army] General Classification Test scores as a measure of cognitive ability. We will update fact and cause of death for all of the twins. During the period of this application, all of these data will be deposited to initiate a data archive located at the National Archive of Computerized Data on Aging (NACDA) at the University of Michigan. Selected twins have also participated in sub-studies where data include screening for cognition and various complex diseases, in-person medical examinations and resulting diagnoses, and genotyping. We have secured the agreement of many of the researchers conducting these projects and during this grant period we will develop specific plans subsequently to bring these data into the archive. We will also do pilot work preliminary to linking to Medicare and Social Security records. Finally, we will use information already on microfiche at MFUA and explore other sources of information to create measures of the men's war experiences and exposure to combat. We will use the data to address the following illustrative research questions: (a) We will test whether moderate drinking is protective against cardiovascular disease and diabetes, relative to abstaining and heavier drinking. If there is a protective effect, we will test whether it is consistent with a direct effect of alcohol or mediated by unmeasured genetic and environmental factors or by measured lifestyle factors such as diet and physical activity. (b) Longitudinal analyses of this twin sample will allow us to separate genetic and early life conditions to see the independent effects of later life circumstances and trajectories. For example, we will evaluate socioeconomic and cognitive differences in health outcomes and longevity over the lifecycle. Knowing education at enlistment, subsequent education obtained under the GI bill, and life time income stream we can look at how these factors are related to treated medical conditions and the length of life. These are only illustrative of the richness of the data and the work that other scientists will be able to carry out as the data archive is created.
We propose to establish a data archive comprised of prospective longitudinal data from 15,924 white male twin pairs born 1917-1927 in which both members of the pair were in the military, most of whom are now deceased. The archive will be a rich resource for investigations of longevity, health disparities, potentially modifiable risk factors associated with medical and behavioral outcomes, and long-term effects of earlier-life exposures. A twin design offers the additional benefit of adjusting for unmeasured genetic and family environmental factors, something not possible in standard case-control epidemiologic studies, in order to give clearer answers to how earlier influences lead to subsequent differences in life trajectories and outcomes, and how later exposures exert their effects, after adjusting for earlier influences.