Aging Issues since 1950
Aging Issues since 1950
The study of aging, or gerontology, is a unique discipline that has emerged during the last half of the twentieth century. Advances in gerontology have been the result of a growing understanding of biomedical functions, behavior, and societal problems. Gerontology cuts across the major disciplines of biology, medicine, psychology, sociology, and even law to form a distinct discipline.
At the end of the twentieth century, only about 70,000 out of the 273 million people in the United States lived to be 100 years of age. Demographers, who study populations and trends, tell us that by 2050 the number of centenarians could swell to 4.2 million. The twenty-first century could thus be known as the age of longevity. A child born today in the United States may live well into the twenty-second century. On May 31, 1974, Public Law 93-296 authorized the National Institute of Aging (NIA) to address the multi-faceted subjects of longevity and the process of aging.
Fear of aging, or gerontophobia, is nothing new. The Greek poet Homer pointed out that even the gods detest old age. In her book Coming of Age, Simone deBeauvoir described a vast literature by writers—ranging from Aristotle to William Butler Yeats—who decried growing old. That people reach a certain point and then slowly deteriorate until death is a myth that persists; youth culture is alive and well today.
A child born in 1776 might have expected to live to age 35; the median age at the time was 16. By the beginning of the 1900s, life expectancy had increased to 40 with a median age of 21. The term "average life expectancy" refers to the age at which, out of a group of people born at the same time, half are alive and the other half have died. For example, in 1999 a person who was born in 1922 had an average life expectancy of 77, meaning that half the people born in 1922 were alive and half had died.
In the minds of many people the year of decline is the age of 65. How this age was chosen is a story that begins in 1885. Bismarck, the chancellor of Germany, had some younger generals whom he wanted to promote but could not because of a group of older officers. To move these older ones out, Bismarck set an arbitrary age of 65 and offered the generals a pension to retire. In 1933, when President Franklin D. Roosevelt started looking at social security as part of the New Deal, he also chose the age of 65, a reasonable age considering that in the 1930s life expectancy was about age 60. What no one had planned for, however, was the intervention of science, which made life expectancy soar as well as the number of Americans living well past the age of 65.
In 1940 several far-sighted scientists such as Thomas W. Parran, the U.S. Surgeon General, recognized that to improve a nation's health research must focus on aging. Nathan W. Shock came to the NIA/Gerontology Research Center (GRC) in 1941 and set up a program, beginning in 1958, that recruited 650 males, ages 26 to 90, to participate in a study on aging. That program became known as the Baltimore Longitudinal Study of Aging. (A longitudinal study uses the same subjects over a period of years.) Volunteers reported to the center every two years for extensive tests involving physical, mental, behavioral, and social factors. About twenty years later, women were added to the study. Shock, often called "the father of aging research," was the primary influence in making gerontology an independent discipline.
When the Research on Aging Act was signed into law in 1974, the NIA/GRC went into action, appointing Robert N. Butler as permanent director in 1976. Many foundations have also been involved in the study of aging as well as groups dedicated to understanding certain diseases related to aging such as Alzheimer's disease.
The maximum human life span refers to the longest period of time a human could live if untouched by disease. At present, scientists believe that age to be about 120 years. The oldest documented person was Jeanne Calment (of France), who died in 1997 at the age of 120. While the average life expectancy has increased over the years, a debate exists as to whether life span can be extended. Roy Wolford, a professor of pathology at the UCLA School of Medicine, believes that the outer limit of the human life span has not budged. In contrast, John Wilmoth, a demographer at the University of California, thinks that there may be no fixed limit if disease is conquered. For example, Thomas E. Johnson and his colleagues at the University of Colorado have extended the life span of a roundworm, C. elegans; they have found eight genes that quadruple the worm's life span, which would equate to a human life span of 340 years.
A perhaps more reasonable goal for science is the "rectangularization of the curve." This term refers to the use of quality medicine to increase the average life expectancy so that average life expectancy will increase to that of life span. In other words, people would remain healthy to the end of their life span, at which point they would die suddenly. Conquering cancer, heart disease, and genetic diseases could achieve this goal. As John H. Bland stated in his book Live Long, Die Fast: "My goal is to die young as late as possible." Instead of tampering with the biological clock, the goal of aging research is to increase life satisfaction and productivity. Research is grouped into the following areas: cellular and genetic, body systems, mental and cognitive, and psychosocial.
Most gerontologists believe the answer lies with cells and genetics. Aging at the cellular level involves cell membranes and their receptors, growth factors, the skin and cartilage, and cellular communication. Leonard Hayflick, a professor of anatomy at the University of California, San Francisco is an authority on the cellular biology of aging and originator of the "Hayflick limit." Hayflick devised this theory in the 1960s after demonstrating that cells divide only a limited number of times and then die. Hayflick states that aging in biological terms defies definition, involving not just the passage of time but what happens over a period of time. Each person has a separate biological clock, and because of that fact biological age does not necessarily fit chronological age. A group of seventy-year-olds, therefore, are much more diverse in age than a group of sixteen-year-olds—biologically.
Some biologists believe that aging is genetic chaos. As one ages, they argue, many genes suddenly stop working. Hayflick thinks we are asking the wrong question when we ask why we age. The correct question, he maintains, should be why do we live as long as we do. Therefore, we should be searching for genes that protect vital life processes, not searching for genes that cause aging.
Hayflick's limit has been verified in the test tube. A cell will divide about fifty times and then die. At the end of the DNA chain is a minute unit called a telomere. Each time DNA replicates, a little bit of the telomere is broken off, and the cell ultimately loses its ability to divide. The telomere gene is turned on in cancer cells, allowing them to multiply wildly. A corporation in Menlo Park, California has isolated the telomere gene and has used it to see if other cells could also live longer.
Mapping the human genome has led to a mad rush to develop drugs to conquer disease at the genetic level. Gene therapy, while now in its infancy, is targeting such diseases as Alzheimer's, an insidious condition in which neurons develop tangles, called neurofibrillary tangles. Early onset Alzheimer's disease has been traced to genes on chromosomes 21, 14, and 1. Late onset Alzheimer's is related to chromosome 19. In 1999 a pharmaceutical company announced success with a vaccine against Alzheimer's in mice that are bred to have Alzheimer's-like symptoms. Researchers are also investigating diseases that resemble premature aging, such as progeria, Werner's syndrome, and Down's syndrome.
Another aspect of the biology of aging is the study of different body systems. For example, if the heart is free of disease, the heart of an older person is as efficient as a younger person's. According to the Centers for Disease Control, death resulting from heart disease has dropped by 60% since 1950. Also, stroke deaths dropped form 88.8 per 100,000 to 26.5 per 100,000 individuals in 1996. Attention to better nutrition, exercise, and quitting smoking account for these improvements. According to longitudinal studies, however, one system that is directly affected by aging is the urinary system. Likewise, the immune system seems to be affected by aging. The ability of the body to produce antibodies diminishes with age and the immune system becomes less able to function. Many ailments of older adults are immune system problems. Arthritis, which has over 100 forms, is an auto-immune disease in which the body turns on itself.
An item related to lifestyle involves the production of free radicals, highly reactive chemicals that combine with other body chemicals, causing them to change. As free agents, they roam about the bloodstream, pairing with other electrons in proteins, lipids, or DNA. Diets high in anti-oxidants help to search out these damaging free radicals. The free-radical theory was developed by Denham Harmon of the University of Nebraska.
One major myth about aging is that older people lose their memory and intellectual abilities. Long-term studies have contradicted these myths. While people do vary according to social and physical conditions, longitudinal studies show that one's level of competence improves as one grows older. Crystallized intelligence (intelligence that depends on learning and experience) increases, although fluid intelligence declines. (Fluid intelligence relates to quickness and rote memory.) The primary effect of aging on intelligence seems to be a decline in the amount of material that a person can learn quickly during a finite period of time. Personality traits also relate to learning; as one researcher has said, having the mental toughness not to succumb to the stereotypes of old age is the most powerful tool against aging. The decline of cognitive skills in older adults is more related to disease (Alzheimer's, tumors, stroke), poor health habits, or depression. Experiments in rats show that in the absence of disease or stress the aging brain does not decline in cognitive intelligence.
The social aspects of aging are also a major area of research. Social Security and Medicare are bounced around in political discussions. Moreover, several groups, such as the American Association of Retired Persons (AARP), the Older Women's League (OWL), and the Gray Panthers, are activists in fighting "ageism," discrimination against people because of their age. Other age-related issues include elder abuse, long-term care of the elderly, and custodial care.
EVELYN B. KELLY
Bland, John. Live Long, Die Fast. Minneapolis: Fairview, 1997.
Chopra, Deepak. Ageless Body, Timeless Mind. New York: Crown, 1993.
Hayflick, Leonard. How and Why We Age. New York: Ballantine, 1994.
Roizen, Michael, and Elizabeth Stephenson. Real Age: Are You As Young As You Can Be? New York: HarperTrade, 1999.
Rosenfeld, Isadore. Live Now, Age Later. New York: Warner, 1999.