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.

Pursuing the longevity dividend: scientific goals for an aging world.

The aging of humanity is about to experience a radical change as the demographic transformation to an older world is approaching its final stage. In recent decades, scientists have learned enough about the biological aging processes that many believe it will become possible to slow aging in humans. We contend that the social, economic, and health benefits that would result from such advances may be thought of as "longevity dividends," and that they should be aggressively pursued as the new approach to health promotion and disease prevention in the 21st century. The time has arrived for governments and national and international healthcare organizations to make research into healthy aging a major research priority.

Early environmental origins of neurodegenerative disease in later life.

Parkinson disease (PD) and Alzheimer disease (AD), the two most common neurodegenerative disorders in American adults, are of purely genetic origin in a minority of cases and appear in most instances to arise through interactions among genetic and environmental factors. In this article we hypothesize that environmental exposures in early life may be of particular etiologic importance and review evidence for the early environmental origins of neurodegeneration. For PD the first recognized environmental cause, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), was identified in epidemiologic studies of drug abusers. Chemicals experimentally linked to PD include the insecticide rotenone and the herbicides paraquat and maneb; interaction has been observed between paraquat and maneb. In epidemiologic studies, manganese has been linked to parkinsonism. In dementia, lead is associated with increased risk in chronically exposed workers. Exposures of children in early life to lead, polychlorinated biphenyls, and methylmercury have been followed by persistent decrements in intelligence that may presage dementia. To discover new environmental causes of AD and PD, and to characterize relevant gene-environment interactions, we recommend that a large, prospective genetic and epidemiologic study be undertaken that will follow thousands of children from conception (or before) to old age. Additional approaches to etiologic discovery include establishing incidence registries for AD and PD, conducting targeted investigations in high-risk populations, and improving testing of the potential neurologic toxicity of chemicals.

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.

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.

Achieving and maintaining cognitive vitality with aging.

Cognitive vitality is essential to quality of life and survival in old age. With normal aging, cognitive changes such as slowed speed of processing are common, but there is substantial interindividual variability, and cognitive decline is clearly not inevitable. In this review, we focus on recent research investigating the association of various lifestyle factors and medical comorbidities with cognitive aging. Most of these factors are potentially modifiable or manageable, and some are protective. For example, animal and human studies suggest that lifelong learning, mental and physical exercise, continuing social engagement, stress reduction, and proper nutrition may be important factors in promoting cognitive vitality in aging. Manageable medical comorbidities, such as diabetes, hypertension, and hyperlipidemia, also contribute to cognitive decline in older persons. Other comorbidities such as smoking and excess alcohol intake may contribute to cognitive decline, and avoiding these activities may promote cognitive vitality in aging. Various therapeutics, including cognitive enhancers and protective agents such as antioxidants and anti-inflammatories, may eventually prove useful as adjuncts for the prevention and treatment of cognitive decline with aging. The data presented in this review should interest physicians who provide preventive care management to middle-aged and older individuals who seek to maintain cognitive vitality with aging.

Selected as the best paper in JAGS in the 1970s mission of the National Institute on Aging.

The National Institute on Aging (NIA), the newest of the 11 National Institutes of Health, is dedicated to improving the quality of life of the old in America through biomedical, social, and behavioral research. Aging is viewed as more than just decline and deterioration; it is also a process of continued development and accumulated knowledge. The NIA will encourage innovative research but will not support the delivery of health services, as that is the domain of the other agencies. In areas of overlap, such as diseases common to the old, the NIA will collaborate with other Institutes. A good target area for collaboration is senile dementia. Other areas of interest to the NIA are: encouraging the incorporation of geriatric medicine as a subspecialty, developing retirement test patterns, and investigating drug-drug and drug-age interactions, personality and social processes, and immunocompetence.

Is there an antiaging medicine?

In spite of considerable hype to the contrary, there is no convincing evidence that currently existing so-called "antiaging" remedies promoted by a variety of companies and other organizations can slow aging or increase longevity in humans. Nevertheless, a variety of experiments with laboratory animals indicate that aging rates and life expectancy can be altered. Research going back to the 1930s has shown that caloric restriction (also called dietary restriction) extends life expectancy by 30-40% in experimental animals, presumably at least partially by delaying the occurrence of age-dependent diseases. Mutations that decrease production of insulin growth factor I in laboratory mammals, and those that decrease insulin-like signaling in nematodes and fruit flies, have increased life expectancy as well. Other general strategies that appear promising include interventions that reduce oxidative stress and/or increase resistance to stress; hormone and cell replacement therapies may also have value in dealing with specific age-related pathologies. This article reports the findings of a consensus workshop that discussed what is known about existing and future interventions to slow, stop, or reverse aging in animals, and how these might be applied to humans through future research.

Biomarkers of aging: from primitive organisms to humans.

Leading biologists and clinicians interested in aging convened to discuss biomarkers of aging. The goals were to come to a consensus, construct an agenda for future research, and make appropriate recommendations to policy makers and the public-at-large. While there was not total agreement on all issues, they addressed a number of questions, among them whether biomarkers can be identified and used to measure the physiological age of any individual within a population, given emerging information about aging and new technological advances. The hurdles to establishing informative biomarkers include the biological variation between individuals that makes generalizations difficult; the overlapping of aging and disease processes; uncertainty regarding benign versus pathogenic age-related changes; the point at which a process begins to do damage to the organism, and, if so, when does it occur; and when to distinguish critical damage from noncritical damage. Finally, and significantly, it is difficult to obtain funding for this research.

Maintaining cognitive health in an ageing society.

A significant concern associated with growing old is the loss of cognitive function, resulting in dementia. Fortunately, the current research on ageing indicates that cognitive decline is not an inevitable function of the ageing process. Moreover, individuals can take steps to maintain cognitive health throughout life. This paper reviews the research findings and recommendations for maintaining cognitive health that were presented at a meeting sponsored by the Alliance for Health and the Future in November 2003. The meeting, 'Placing Cognitive Health on Europe's Social and Economic Agenda', reviewed the current state of knowledge about cognitive health and discussed its implications for an ageing Europe. Although the brain, for reasons that remain unclear, changes with age, a growing body of research suggests that social engagement, intellectual stimulation, and physical activity play a key role in maintaining cognitive health and preventing cognitive decline. As the number of older people increases and people live longer, developing and implementing strategies for maintaining cognitive health should be a priority for both individuals and societies.

Better care for our aging.

All physicians need to receive basic education and training in the care of older people during their medical studies to ensure adequate and appropriate health care of our aging population. The benefits of this will be felt across the entire health care spectrum, including home care and hospice.

The demographic and biomedical case for late-life interventions in aging.

The social and medical costs of the biological aging process are high and will rise rapidly in coming decades, creating an enormous challenge to societies worldwide. In recent decades, researchers have expanded their understanding of the underlying deleterious structural and physiological changes (aging damage) that underlie the progressive functional impairments, declining health, and rising mortality of aging humans and other organisms and have been able to intervene in the process in model organisms, even late in life. To preempt a global aging crisis, we advocate an ambitious global initiative to translate these findings into interventions for aging humans, using three complementary approaches to retard, arrest, and even reverse aging damage, extending and even restoring the period of youthful health and functionality of older people.