Aging: Physical changes
Introduction (Psychology and Mental Health)
The human life span (the length of time people may live under optimal conditions) is about 120 years. Although this figure has not changed over the last century, life expectancy has. The amount of time an American baby can be expected to live has increased from under sixty years if born in 1900 to nearly seventy-seven years if born in 2002. As people have begun to live longer, they have become aware of many changes that occur as they age. The scientists who study aging are called gerontologists. It is known that predictable changes occur in the body as it gets older. Some are easily noticed, such as graying or thinning hair and wrinkles. Other changes, such as a tendency toward rising blood pressure, are not visible.
In general, research on aging has emphasized losses. More recently, increased interest in the aging process has stimulated physiological, sociological, and psychological research on aging. Although many physiological variables show major losses with advancing age, it is important, when looking at the average, to note that there is substantial variability at all ages throughout life. Scientists have found that some changes in blood pressure and cholesterol levels that had originally been interpreted as age specific are common in industrial societies but not in agricultural ones.
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Changes in Body Systems with Age (Psychology and Mental Health)
One of the major physical changes that occurs with age is an increase in reaction time. As one gets older, it takes longer to respond to a stimulus. This increased reaction time is due to a number of factors, including changes in sensory function, an increased concern for accuracy, a slower response (often due to arthritis), and a slowing of transmission of neural impulses. This slowdown in the transmission of impulses through the nervous system is due in large part to demyelinization. As the axons lose their fatty covering (myelin sheath), saltatory conduction is impaired, and slowing of the neural impulse occurs.
Advancing age is associated with progressive impairments in the capacity to metabolize glucose. Again, there is substantial variability in the results for successive age groups, with many older individuals metabolizing glucose as well as their younger counterparts. The carbohydrate intolerance of aging may carry substantial risk, even in the absence of disease. Attempts have been made to determine which components of the age-associated alterations in carbohydrate intolerance are related to aging itself and which components might be related to diet, exercise, or medications. It is thought that factors such as physical fitness may decrease the likelihood of carbohydrate intolerance with advancing age. Metabolism also begins to slow at around age twenty-five. For each decade thereafter, the number of...
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Theories of Aging (Psychology and Mental Health)
Virtually all systems of the body, including the cardiovascular, circulatory, endocrine, excretory, and gastrointestinal systems, show changes with age. Several theories attempt to explain the aging process. The aging of cells is a complex process that scientists still do not completely understand. There are genetic theories, as well as nongenetic and physiological ones. Genetic and nongenetic theories of aging both explain aging at the cellular or molecular level.
Genetic theories assume that a problem occurs in cell formation with age. This problem occurs at the level of the ribonucleic acid (RNA) or deoxyribonucleic acid (DNA). Error theory is the genetic theory best supported by evidence, and it assumes that aging is most likely to occur as a result of a change in RNA.
Nongenetic theories assume that cell formation occurs normally with age but that something interferes with cell functioning as one ages. Wear-and-tear theory and accumulation theory are two of the best-supported nongenetic theories. The buildup of free radicals in the cell (which fits accumulation theory) has led to the popular use of antioxidants (nutritional supplements) to try to slow the aging process.
Physiological theories assume that aging occurs at the molar level—the level of tissues, organs, or systems. These theories attribute aging to a breakdown in the integration and function of systems. Evidence indicates support for some...
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Trends in Aging (Psychology and Mental Health)
The number of elderly people in the United States has increased rapidly in recent years. In the second half of the twentieth century, the number of Americans sixty-five or older more than doubled. Americans are living longer than ever before. The Bureau of the Census predicts that, by 2030, the number of elderly Americans will grow to nearly 65 million and that this demographic will make up more than 20 percent of the population. It is estimated that by 2050, one in twenty Americans will be older than eighty-five years of age.
One popular misconception disputed by recent research is the idea that aging means inevitable physical and sexual failure. Although some changes necessarily occur, many of the problems associated with old age fall into the category of secondary aging. Such problems are not the result of age but of abuse and disuse, which often can be controlled by the individual. Researchers have found that people wear out faster from disuse than they wear out from overuse. This also applies to sexuality. Studies from the time of Alfred Kinsey’s work in the 1940’s and 1950’s to the early twenty-first century show that sexual interest and activity decrease with age, but the drop varies greatly among individuals. Psychologist Marion Perlmutter reported that one of the best predictors of continued sexual intercourse is past sexual enjoyment and frequency. People who have never enjoyed sexuality much may consider age...
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Studies on Aging (Psychology and Mental Health)
Important early studies of aging were performed in the 1950’s, including the Human Aging Study, conducted by the National Institute of Mental Health; the Duke Longitudinal Studies, done by the Center for the Study of Aging and Human Development at Duke University; and the Baltimore Longitudinal Study of Aging. These pioneering studies and hundreds of others have benefitted from growing federal support.
The Human Genome Project (especially Project Chronos) is among studies important in the field of aging. These studies continue to investigate the changes that take place in aging, as well as attempting to find ways to stop or delay these changes. In contemporary society, many people reaching one hundred years of age (centenarians) continue to function very well, showing minimal physical change with age. As these people are studied in projects such as Chronos, perhaps humankind will find an answer to the biological changes in aging, as well as finding ways to delay such changes.
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Sources for Further Study (Psychology and Mental Health)
Birren, James E., and K. Warner Schaie, eds. Handbook of the Psychology of Aging. 6th ed. Boston: Elsevier Academic Press, 2006. Presents information on the psychology of adult development and aging in an edited handbook format. Provides the reader with chapters written by experts on a wide range of topics. An authoritative review, serving as a definitive reference source for students, researchers, and professionals.
Hoyer, William J., and Paul A. Roodin. Adult Development and Aging. 5th ed. Boston: McGraw-Hill, 2003. This college-level text covers all aspects of human aging with helpful information about physiological changes and physical health.
Masoro, Edward J., and Steven N. Austad, eds. Handbook of the Biology of Aging. 6th ed. Boston: Elsevier Academic Press, 2006. A definitive source reviewing biological changes with aging. It covers the most interesting topics in biomedical gerontology.
Schaie, K. Warner, and Sherry L. Willis. Adult Development and Aging. 5th ed. Upper Saddle River, N.J.: Prentice Hall, 2002. This college-level text provides an overview to the field of human aging focusing on physical aspects in part 2 of the text.
Whitbourne, Susan Krauss. Adult Development and Aging: Biopsychosocial Perspectives. 3d ed. Hoboken, N.J.: John Wiley, 2008. Synthesis of psychological, biological, and sociological perspectives on age and...
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