Studies on exceptional human longevity may provide important clues on possible factors and mechanisms that delay human aging and promote healthy life span. This epidemiological approach to unraveling the mechanisms of human aging and longevity is applied in this study using two different datasets.
The first study explored the determinants of exceptional survival to age 100 and beyond using data on American centenarians having detailed information on their parents and siblings. The validated centenarians born in USA in 1890-1893 were identified, and their complete family histories were reconstructed using early US Censuses, the US Social Security Administration database, genealogical records and other supplementary data resources. A method of within-family analysis has been applied to compare centenarians with their shorter-lived siblings, which allows researchers to avoid confounding caused by between-family variation. The following predictor variables were explored: person's sex, birth order, paternal age at person's birth, maternal age at person's birth, and the season of birth. The study found that being born to young mother (younger than 25 years) is the major predictor of person's longevity. Moreover, even at age 75 it still helps to be born to young mother in order to become a centenarian. These findings are consistent with the 'best eggs are used first' hypothesis suggesting that earlier formed oocytes are of better quality, and go to fertilization cycles earlier in maternal life.
The second study explores whether people living to 100 and beyond were any different in physical characteristics from their peers at their middle age (30 years). A random sample of men born in 1887 and survived to age 100 was selected from the US Social Security Administration database and then linked to the US WWI draft registration cards collected in 1917 when these men were 30 years old. Randomly selected shorter-lived men matched by birth year, race and county of draft registration were used as controls. It was found that the 'stout' body build (being in the heaviest 15% of population) was negatively associated with survival to age 100 years. Both farming and having large number of children (4+) at age 30 significantly increased the chances of exceptional longevity by 100-200%. The effects of immigration status, marital status, and body height on longevity were less important, and they were statistically insignificant in the studied data set. This study provides the first estimates of height, body build and other vital characteristics for the future centenarians at their young adult ages, and shows that detrimental effects of obesity may have an exceptionally long time range, and that obesity at young adult age (30 years) is predictive for almost three times lower chances of survival to age 100 years.
These two studies demonstrate that early-life and mid-life living conditions play an important role in exceptional longevity. Both studies are supported by the grant from the U.S. National Institute on Aging (R01 AG028620).
For more information, please see our earlier publications on related topics:
1. Gavrilova N.S., Gavrilov L.A. Can exceptional longevity be predicted? Contingencies [Journal of the American Academy of Actuaries], 2008, July/August issue, pp. 82-88.
2. Gavrilova N.S., Gavrilov L.A. Physical and Socioeconomic Characteristics at Young Age as Predictors of Survival to 100: A Study of a New Historical Data Resource (U.S. WWI Draft Cards). Living to 100 and Beyond: Survival at Advanced Ages [online monograph]. The Society of Actuaries, 2008, 23 pages.
3. Gavrilova N.S., Gavrilov L.A. Search for Predictors of Exceptional Human Longevity: Using Computerized Genealogies and Internet Resources for Human Longevity Studies. North American Actuarial Journal, 2007, 11(1): 49-67.