Coping with Methuselah: The Impact of Molecular Biology on Medicine and Society

by Henry Aaron, William B. Schwartz

Overview

"Many medical authorities predict that average life expectancy could well exceed 100 years by mid century and rise even higher soon thereafter. This astonishing prospect, brought on by the revolution in molecular biology and information technology, confronts policymakers and public health officials with a host of new questions. How will increased longevity affect local and global demographic trends, government taxation and spending, health care, the workplace, Social Security, Medicare, and Medicaid? What ethical and quality-of-life issues are raised by these new breakthroughs? In Coping with Methuselah, a group of practicing scientists and public policy experts come together to address the problems, challenges, and opportunities posed by a longer life span. This book will generate discussion in political, social, and medical circles and help prepare us for the extraordinary possibilities that the future may hold.

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Product Details

ISBN-13:	9780815700395
Publisher:	Rowman & Littlefield Publishers, Inc.
Publication date:	01/20/2004
Edition description:	New Edition
Pages:	296
Product dimensions:	6.02(w) x 8.98(h) x 0.76(d)

About the Author

Henry J. Aaron is a senior fellow in Economic Studies at the Brookings Institution, where he holds the Bruce and Virginia MacLaury Chair. Among his many books are "Can We Say No? The Challenge of Rationing Health Care," with William B. Schwartz and Melissa Cox (Brookings, 2006), and "Reforming Medicare: Options, Tradeoffs, and Opportunities," written with Jeanne Lambrew (Brookings, 2008). William B. Schwartz is an expert on national health policy and is a professor of medicine at the University of Southern California. He was formerly chairman of the Department of Medicine and Vannevar Bush Professor at Tufts University and was also president of the American Society of Nephrology.

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Coping with Methuselah

The Impact of Molecular Biology on Medicine and Society

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By Henry J. Aaron

Brookings Institution Press

Copyright © 2004 Henry J. Aaron
All right reserved.
ISBN: 0815700407

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Introduction

The capacity to manipulate the genetic templates that shape all living beings was long the plaything of science fiction. That humans could mold the biological determinants of their own character was eerie and unreal. But then, in the final decades of the twentieth century, intellectual alchemy transmuted genetic tinkering from dream into reality. In 1953 two young scientists identified the double helix, composed of four nucleotides, containing the code of all life. In so doing they opened the first chapter in the saga of molecular biology. In 2001 two scientific teams, competing to read the components of the human genome, wrote another chapter. But these events are the barest beginnings of the gradually emerging understanding of the forces that shape humans, that cause them to sicken, and that eventually cause them to die.

Commentators still remain free to imagine futures as they will, much as observers of the first steps of industrialization saw quite different worlds emerging from the new machines. Some looked at machines and saw dehumanization and the demise of skills. Others looked and saw abundance and leisure. What none could fully apprehend was that the vision of people who lived with the new technology would be fundamentally and irreversibly different from that of people who only imagined what the future might hold.

Those alive after the advent of electricity, mass production, modern telecommunications, air travel, and computer science have been shaped by those technologies in ways that those born in earlier times could not imagine. Not even the cleverest person in 1800 could fathom the effects of these future technologies, not least because they could not even imagine what all of those technologies would be. Nor, perforce, could they see the future through eyes of those who would be alive to experience the as-yet-undiscovered technologies.

The molecular biology century, as the twenty-first century may well be called, will almost certainly change how humans see the world and themselves. Even if an eighteenth-century artisan who had cried jeremiads against the dehumanization of machine production was somehow teleported into the present and said, See, I told you so, we would not take such testimony seriously. Such criticism would be pointless-quaint and irrelevant commentary from inhabitants of a world now as imaginary to us as ours was to them. For these reasons, those who pass moral judgment on the new world to which revolutionary advances in molecular biology will give birth are engaging in a kind of romantic irrelevance-attempting to apply early-twenty-first-century standards to a future world as different from our own as ours is from the artisanal life of the eighteenth century.

We present the following essays in that spirit. We are persuaded that molecular biology will alter human lives and consciousness at least as profoundly as did the industrial revolution, modern telecommunications, mechanized travel, and the information revolution. Side by side with these developments came improvements in public health, nutrition, and medical treatment. Birth rates plummeted. Life expectancies soared. And the content of lives changed.

No one can predict the precise extent or timing of advances in molecular biology. No one can foresee when particular diseases will be prevented or cured. No one can know exactly when or even if human aging will be slowed or stopped. No one yet knows for sure whether the genetic makeup of humans limits life span or, if it does, what those limits might be. Some families include more nonagenerians and centenarians than any roll of nature's dice can explain. This fact suggests that genetic inheritance powerfully influences longevity. Average human life spans longer than any nation's current average may be achievable without genetic tinkering. Even if life span now has limits, molecular biology may reveal that these limits are variables, not constants, and provide ways to slow aging and to prevent or cure illnesses that cause physical decline and death.

The Frontiers of Molecular Medicine

John T. Potts and William B. Schwartz open this volume by describing the channels through which such advances could occur. Humans have been trying to cure their own diseases for millennia. Potts and Schwartz make clear that scientific advance has revolutionized the assault on human illness. Current methods flow directly from the emergence of a detailed understanding of the functioning of human cells and an emerging understanding of the structure and function of human genes and their protein products.

Physicians have long understood, in some sense, the basis of successful medical treatments. Still, the underlying processes by which these interventions worked their magic remained hidden. The first antibiotics, for example, were more or less serendipitous discoveries. The death of bacteria led an astute observer to recognize the potential value of a mold as a source of penicillin for the treatment of infection. Later antibiotics resulted from systematic searches. But the fundamental reasons why antibiotics killed pathogens for decades remained as mysterious to the discoverers and to the physicians who used the drugs as they were to the patients whose lives they saved.

Safe correction of genetic defects through insertion of normal genes into the patient's DNA (dioxyribonucleic acid) seems to be an ever-retreating target. The more promising near-term approach is likely to be through identifying the pathologic proteins specified by an abnormal gene and synthesizing a drug that can offset its effects. Whether progress will be fast or slow cannot be forecast because this new field-structural genomics-must surmount major obstacles before it yields effective therapeutic agents. But expectations are high that intense research-by government-supported scientists and by drug companies with dollar signs dancing before their eyes-will lead to a wide range of breakthrough agents. Portents for the discovery of cures for major diseases within the first half of the twenty-first century are extremely encouraging. If each disease resulted from a single genetic defect, progress could be extremely rapid. Unfortunately, only a few illnesses are directly traceable to a single genetic flaw. Most illnesses result from multiple genetic mutations and the expression of a vast number of proteins. This painful reality guarantees that major resources over many decades will be required to produce the promised cornucopia of new drugs.

Potts and Schwartz provide a tour d'horizon of the multiple frontiers of biomedical advance. No brief chapter can encompass the enormous range of current biomedical research. Nonetheless, their chapter identifies a variety of fields in which progress is particularly encouraging. For example, molecular biology has created a whole new field of therapy: regenerative medicine. Skin, tissue, and whole organs may be grown in the laboratory and implanted in living humans to repair injuries and replace worn-out body components. Organs may soon be grown in animals that have been biologically modified so that human recipients will not reject the organs. Stem cells may be harvested and reimplanted to enable humans to regenerate their own organs-or so cutting-edge researchers believe.

Cancer presents the largest target and what may be the greatest challenges for molecular biology. Cancer results directly from the breakdown of genetic instructions for cell replication. The result is unlimited and uncontrolled cell growth. Understanding the multiple mechanisms by which genes instruct cells on when to divide and to self-destruct and the many ways error creeps into these instructions is the first objective. Techniques designed to check abnormal cell growth include antibodies and enzymes that inactivate the receptors that tell the cell to divide and factors to inhibit growth of the blood vessels that nourish the rapidly growing cancer tissues. Other interventions will facilitate the normal processes of cell death, which are suppressed in cancer cells, or will reverse mutations that block natural body defenses against cancers. In an interesting twist on the virus problem, viruses will be used to infect or poison cancer cells.

Molecular biology also carries hope of preventing or curing cardiovascular illness, the number-one killer disease in the United States. Some people have a genetic predisposition to high levels of the form of cholesterol associated with cardiovascular disease. Interventions to correct this defect or to block it from boosting cholesterol would reduce the likelihood of heart disease. Effective measures to encourage the growth of blood vessels could spare victims of coronary thrombosis from the damage to the heart that results from blocked coronary arteries. Recent work also indicates that inflammation of the coronary arteries may be responsible for as many as half of heart attacks.

Perhaps the greatest medical advance of the twentieth century is the development of antibiotics. Unfortunately, strains of bacteria have emerged that resist all known antibiotics. Now that the genomes of many pathogens have been identified and the genes responsible for the harmful effects have been brought into view, molecular biology represents the best hope of forestalling this threat. With that understanding, scientists will be able to design therapeutic agents that circumvent these bacterial defenses. Prospects are also improving for the development of agents that successfully combat viral infections, which with few exceptions have resisted treatment.

As the twenty-first century begins, the hit-or-miss search for new drugs and for other ways to cure or prevent many illnesses is ending. A new era is emerging in which scientists work from a fundamental understanding of cells, proteins, and genes to design interventions that reverse, block, or otherwise forestall illnesses. In the words of the Nobel prizewinner Alfred Gilman, scientists are now "able to complete [their] understanding of the wiring diagram of the signaling switchboard in each type of cell." With that knowledge in hand, they now-or soon will-have the means to design drugs or to directly change how cells operate to correct the genetic defects that each person inherits or acquires during life from mutations or other sources.

Molecular biology also provides weapons for combating a few illnesses that have become increasingly frequent as incomes have risen-obesity and senile dementia. Increasing incomes and decreasing activity are leading to a veritable epidemic of diabetes and other illnesses of the indolent overfed. An emerging understanding of cell metabolism and the brain chemistry that leads to overeating is helping scientists to find other ways to prevent or lessen the harmful consequences of excessive caloric intake.

While cancer has historically been the paradigmatic dread disease, senile dementia-Alzheimer's disease in particular-has become the new terror of those who can expect to live into old age. With improved understanding of the process by which this disease corrodes cognitive capacity and then destroys personality and physical functioning is coming the realistic prospect of interventions to prevent the disease or forestall its harmful consequences. Whether increased longevity will be a blessing or a curse, for the elderly themselves and for society, hinges in part on the success of this endeavor.

Our Uncertain Demographic Future

Even without accelerated medical advance, demographers project that longevity will increase and that the elderly will comprise a growing proportion of the U.S. population. Biomedical advance could intensify these trends. The reduction in mortality from heart disease by more than 50 percent since 1960 demonstrates the feasibility of such improvements.

Henry J. Aaron and Benjamin H. Harris explore the demographic implications of accelerated reductions in mortality rates and review various demographic models for human mortality. One such model suggests that reductions in mortality rates could average 2 percent a year, approximately the rate of decline in Japan during the 1970s and 1980s. According to another view, mammalian life span has a natural limit. After reproduction, it is argued, survival serves no useful evolutionary purpose, and early demise after reproduction may aid evolutionary success by reducing pressure on resources. The finding by the nineteenth-century scientist August Weismann that cells stop reproducing after a certain number of divisions seems consistent with this hypothesis.

Even if a natural limit exists, however, the practical questions are whether that limit is near or much above current average life span and what can be done to modify those processes. Aaron and Harris conclude that the most helpful theory of the aging process is an analogy of humans to a machine that consists of many components, each essential for the machine's operation. Each component remains functional until too many of its constituent parts fail. Engineers have shown that machines fail over time in patterns that closely resemble human mortality rates. The machine model suggests that medical progress comes through interventions that prevent or postpone the failure of the constituent parts of each of the biological systems essential for life.

Rapid reductions in mortality rates quickly affect longevity but alter the population profile only with considerable delay. Social Security Administration projections, which assume no acceleration in reductions in mortality rates, posit that people born in 2030 will have a life expectancy at birth of just over 84 years; for those born in 2075, the average is 86 years. But if mortality rates decline 2 percent a year, babies born in 2030 could expect to live 104 years, and those born in 2075, more than 115 years. Even this rapid rate of improvement would not have much effect on the population distribution until the second half of the century. During the first half, the dominant event will be the aging and retirement of the baby-boom generation.

Whether reduced mortality increases or reduces disability depends on whether mortality is measured as years since birth or as years until death. If disability rates depend on years since birth, the number of disabled would skyrocket as the aged population rises. If it depends on years until death, disability would probably change little. The same holds for the cost and burden of supporting the elderly and the disabled. If delayed aging or public policy encourage later retirement, the ratio of retirees to active workers might increase only slightly. If current retirement age patterns persist, however, the cost of increased longevity would rise sharply as people spend ever more years outside of the labor force.

Work

If the proportion of each age group that works is unchanged, declining mortality cannot much affect the labor force.

Continues...

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Excerpted from Coping with Methuselah by Henry J. Aaron Copyright © 2004 by Henry J. Aaron. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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Table of Contents

	Foreword	vii
	Acknowledgments	ix
	Introduction	1
1	The Impact of the Revolution in Biomedical Research on Life Expectancy by 2050	16
	Comment	52
2	Our Uncertain Demographic Future	66
	Comment	94
3	The Changing Face of Health Care	105
4	Labor Market Effects of Dramatic Longevity Improvement	126
	Comment	162
5	The Impact of Major Improvements in Life Expectancy on the Financing of Social Security, Medicare, and Medicaid	166
	Comment	194
6	Ethical Aspects of Major Increases in Life Span and Life Expectancy	198
	Comment	235
7	Increased Life Expectancy: A Global Perspective	247
	Comment	277
	Contributors	285
	Index	287