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Biomedical subjects

S Jay Olshansky

Publications and source records attributed to S Jay Olshansky.

At least 19 recordsLinked to original sources
PubMed2006

Mortality partitions and their relevance to research on senescence.

The reasons for classifying causes of death into aggregate groups are discussed and the impact of mortality partitions on analyses of mortality is described. Special emphasis is given to a mortality partition that distinguishes between intrinsic causes of death that arise primarily from the failure of biological processes that originate within an organism, and extrinsic causes of death that are primarily imposed on the organism by outside forces. Examples involving mortality data for mice, dogs, and humans are used to illustrate how this mortality partition infuses biological reasoning into mathematical models used to analyze and predict senescent-determined mortality, enhances the information content of the mortality schedules generated from these models, improves mortality comparisons between populations within species separated by time or geographic location, and provides a logical pathology endpoint for making interspecies comparisons of mortality. By bridging biology and the statistics of mortality, a mortality partition based on intrinsic and extrinsic causes of death provides both structure and direction for research on senescent-determined mortality.

Aging↗
PubMed2005

Biodemographic perspectives for epidemiologists.

A new scientific discipline arose in the late 20th century known as biodemography. When applied to aging, biodemography is the scientific study of common age patterns and causes of death observed among humans and other sexually reproducing species and the biological forces that contribute to them. Biodemography is interdisciplinary, involving a combination of the population sciences and such fields as molecular and evolutionary biology. Researchers in this emerging field have discovered attributes of aging and death in humans that may very well change the way epidemiologists view and study the causes and expression of disease. In this paper, the biodemography of aging is introduced in light of traditional epidemiologic models of disease causation and death.

Journal Article↗
PubMed2005

Misdirection on the road to Shangri-La.

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Journal Article↗
PubMed2005

Aging down under.

A new International Research Centre for Healthy Ageing and Longevity (IRCHAL) has been created in Australia with initial funding from a philanthropic family--that of John and Noah Weller. This center will be akin to the Center for Advanced Study at Stanford University where scientists and clinicians/geriatricians can spend extended time periods interacting and doing their research. The development of IRCHAL is an explicit effort to blend traditional scientific approaches to the study of aging with evidence-based natural and complementary medicine. At the heart of this new organization are annual international scientific conferences. The next meeting (third in the series) will be held in Melbourne, Australia, on 28 to 30 April 2006.

Aged↗
PubMed2005

Misdirection on the road to Shangri-La.

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Adolescent↗
PubMed2005

A potential decline in life expectancy in the United States in the 21st century.

Forecasts of life expectancy are an important component of public policy that influence age-based entitlement programs such as Social Security and Medicare. Although the Social Security Administration recently raised its estimates of how long Americans are going to live in the 21st century, current trends in obesity in the United States suggest that these estimates may not be accurate. From our analysis of the effect of obesity on longevity, we conclude that the steady rise in life expectancy during the past two centuries may soon come to an end.

Aged↗
PubMed2005

At the heart of aging: is it metabolic rate or stability?

Foundational changes in science are rare, but in the field of biogerontology there is a new theory of aging that may shake things up. The conventional wisdom about duration of life is based on an old idea known as the "rate of living" theory, which suggests that aging is caused by the loss of some vital substance. The modern version of this theory is that duration of life is influenced by the relative speed of a species' resting metabolism. However, empirical evidence does not consistently support this hypothesis. In an article published recently by mathematician/biologist Lloyd Demetrius, it is suggested that the most important factor involved in duration of life is not metabolic rate or oxidative stress, but metabolic stability. If Demetrius is correct, his theory will have important implications for intervention research. For example, if the metabolic rate/oxidative stress theory is correct, efforts to intervene in the aging process should be directed at finding ways to reduce metabolic rate, lessen the production of reactive oxygen species (ROS), improve antioxidant defenses, or increase the quantity of antioxidants. If the metabolic stability hypothesis is correct, efforts to intervene in the aging process should be directed at finding ways to increase the stability of the steady state values of ROS, increase the robustness of metabolic networks, or improve the stability of antioxidant enzymes. For now there is reason to believe that Demetrius' theory deserves further consideration - whether it meets the test of a paradigm shift has yet to be determined.

Aging↗
PubMed2005

Projecting the future of U.S. health and longevity.

Is the health of the U.S. population improving or getting worse, and how are health and medical costs influenced by obesity? How will anticipated advances in the biomedical sciences influence life expectancy and the cost of health care? The paper by Dana Goldman and colleagues is a daring speculation on the life-extending effects of possible future technologies--a valuable exercise given the speed of technological advances. Darius Lakdawalla and colleagues provide a methodologically solid basis for concluding that not only does obesity kill, it also takes an alarming toll on health and health care spending at levels that require immediate intervention.

Health Expenditures↗
PubMed2003

Biological evidence for limits to the duration of life.

Projections of duration of life for humans based on mathematical models have led some researchers to claim that there is no lower limit to death rates or upper limit to life expectancy, and that a life expectancy of 100 will be achieved in the 21st century. To assess the biological plausibility of these claims, we examined temporal aspects of biological phenomena in three mammalian species. Our examination revealed that: (1) physiological declines associated with reproduction consistently occur at ages that are less than one-third of the median age at death, (2) physiological parameters associated with aging in humans lose eighty percent of their functional capacity by age 80, and (3) young versus old individuals can be distinguished by the pathologies detected at death. The biological evidence suggests that organisms operate under warranty periods that limit the duration of life of individuals and the life expectancy of populations. We use these findings to discuss the issue of limits to the duration of life and the validity of mathematical models used to forecast human longevity.

Age Factors↗
PubMed2003

Anti-aging teleconference: what is anti-aging medicine?

The concepts of "anti-aging" and "anti-aging medicine" in particular are hotly debated now, both in the mass media and among some researchers. This paper represents an open discussion of anti-aging terms and related ideas by nine leading experts in the field of aging studies, and it describes in detail the arguments presented by both supporters and opponents of these concepts. Candid exchange of opinions makes it clear that more efforts are required before a consensus on these issues can be reached. The paper also presents evidence that the term "anti-aging" is routinely used now in scientific literature as a legitimate scientific term, including even the titles of publications in reputable scientific journals, written by established researchers.

Aging↗