Aging and death

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Aging and death

Theories on aging

Diseases associated with aging



Aging is the natural effect of time and the environment on living organisms. It is a progressive, predictable process in which gradual changes not caused by disease or accident occur over time. Aging affects both the body and the mind. Some age-related changes start as early as the 20s, while others may not appear until people are in their 70s. Although aging is inevitable, people age at different rates. Age-related changes eventually lead to the increased probability of death as people grow older. Death occurs when all vital functions of the body including heartbeat, brain activity (including the activity of the brain stem), and breathing stop irreversibly. Other signs of death include no pupil reaction to light, no jaw reflex (the jaw will contact involuntarily like the knee if tapped with a reflex hammer), no gag reflex (touching the back of the throat will induce vomiting), and no response to pain.

Gerontology is the study of all aspects of aging. No single theory on how and why people age is able to account for all facets of aging. Although great strides have been made to postpone death as the result of certain illnesses, less headway has been made in delaying aging. Life expectancyhow long people are expected to livehas risen dramatically since 1900, when it was 47 years. In 2004, according to the U.S. Centers for Disease Control and Prevention (CDC),

the average life expectancy for humans is 77.9 years, an average increase of about 110 days each year since 1900.

Life span is species-specific. Members of the same species have similar life expectancies. In most species, death occurs not long after the reproductive phase of life ends. This is obviously not the case for humans. However, there are some changes that occur in women with the onset of menopause when estrogen levels drop. Post-menopausal women produce less facial skin oil (which serves to delay wrinkling) and are at greater risk of developing osteoporosis (brittle bones). Men continue to produce comparable levels of facial oils and are thus less prone to early wrinkling. Osteoporosis occurs as calcium leaves bones and is used elsewhere; hence, sufficient calcium intake in older women is important because bones which are brittle break more easily.

Theories on aging

The relationship between aging and death is complex. The results from many studies indicate that aging decreases the efficiency of the body to operate, defeat infections, and to repair damage. Comparison of people aged 30 to 75 years has demonstrated that the efficiency of lung function decreases by 50% that bones become more brittle, and that the immune system that safeguards the body from infections generally becomes less efficient as humans age.

Why this deterioration in the functioning of the body with age occurs is still not clear. Several theories have been proposed to explain this decline. One theory proposes that after the active years of reproduction have passed, chemical changes in the body cause the gradual malfunctioning of organs and other body components. The accumulation of damage to components that are necessary for the formation of new cells of the body leads to death. For example, it has been discovered that the formation of the genetic material deoxyribonucleic acid (DNA) is more subject to mistakes as time goes on. Other theories relating aging with death include the negative effect of stresses to the body, and a theory that proposes that the build-up of non-functional material in the body over time lessens the ability of the body to function correctly.

The strongest arguments on the aging process favor involvement of one of, or a combination of the following: hormonal control, limited cell division, gene theory, gene mutation theory, protein cross-linkage theory, and free radical action. In support of hormonal control, there is the observation that the thymus gland (under the sternum) begins to shrink at adolescence, and aging is more rapid in people without a thymus. Another hormonal approach focuses on the hypothalamus (at the base of the brain), which controls the production of growth hormones in the pituitary gland. It is thought that the hypothalamus either slows down normal hormonal function or that it becomes more error-prone with time, eventually leading to physiological aging.

More recent theories on aging come from cellbiology and molecular biology. Cells in culture in the laboratory keep dividing only up to a point, and then they die. Cells taken from embryos or infants divide more than those taken from adults. Hence, it is thought that this is the underlying mechanism of agingonce cells can no longer divide to replenish themselves, a person will begin to die. However, most scientists now accept that most cells (other than brain and muscle cells) are capable of division for a longer time than the normal human lifespan.

Gene theory and gene mutation theory both offer explanations for aging at the level of DNA. Gene theory suggests that genes are somehow altered over time, such that they naturally cause aging. Gene mutation theory is based on the observation that mutations accumulate over time, and it is mutations that cause aging and disease. This view is supported by the fact that samples of cells from older people do generally have more genetic mutations than cells taken from younger people. In addition, some diseases associated with age result from genetic mutations. Cancer is often the result of multiple mutations and some mutations reveal underlying genetic weaknesses, which cause disease in some people. Gene mutation theory also notes that for mutations to accumulate, normal DNA-repair mechanisms must have weakened. All cells have inherent repair mechanisms that routinely fix DNA errors. For these errors to accumulate, the repair system must have gone awry, and DNA-repair failure is thought to be a factor in cancer.

Protein cross-linkage and free radicals are also thought to contribute to aging. Faulty bonds (cross-linkages) can form in proteins with important structural and functional roles. Collagen makes up 25-30% of the bodys protein and provides support to organs and elasticity to blood vessels. Cross-linkage in collagen molecules alters the shape and function of the organs it supports and decreases vessel elasticity. Free radicals are normal chemical byproducts resulting from the bodys use of oxygen. However, free radicals bind unsaturated fats into cell membranes, alter the permeability of membranes, bind chromosomes, and generally alter cellular function, causing damage. Antioxidants, such as vitamins C and E, block free radicals and are suggested for prolonging life.

Diseases associated with aging

Some consequences of aging are age-related changes in vision, hearing, muscular strength, bone strength, immunity, and nerve function. Glaucoma and cataracts are ocular problems associated with aging that can be treated to restore failing vision in older people. Hearing loss is often noticeable by age 50 years, and the range of sounds heard decreases. Muscle mass and nervous system efficiency decrease, causing slower reflex times and less physical strength, and the immune system weakens, making older people more susceptible to infections.

More serious diseases of aging include Alzheimer and Huntington diseases. Patients with Alzheimer disease, also called primary dementia, exhibit loss and diminished function of a vast number of brain cells responsible for higher functions; learning, memory, and judgment are all affected. The condition primarily affects individuals over 65 years of age. Some current figures estimate that as many as 10% of people within this age group are affected by Alzheimer disease. A rapidly expanding disease whose numbers increase as the proportion of elderly Americans continues to rise, it is predicted that 14 million people in the United States will have Alzheimer disease by the year 2050. Huntingtons disease is a severely degenerative malady inherited as a dominant gene. Although its symptoms do not appear until after age 30 years, it is fatal, attacking major brain regions. There is no treatment for either of these age-related diseases.


Death is marked by the end of blood circulation, the end of oxygen transport to organs and tissues, the end of brain function, and overall organ failure. The diagnosis of death can occur legally after breathing and the heartbeat have stopped and when the pupils are unresponsive to light. The two major causes of death in the United States are heart disease and cancer.

Other causes of death include stroke, accidents, infectious diseases, murder, and suicide. While most of these phenomena are understood, the concept of stroke may be unclear. A stroke occurs when blood supply to part of the brain is impaired or stopped, severely diminishing some neurological function. Some cases of dementia result from several small strokes that may not have been detected.

Death is traumatic not only for the dying, but for the people who love them. Individual differences in a persons reaction to death are influenced by many factors such as their family, cultural, and ethnic background, their life experiences, their previous experiences with death, their socioeconomic status and their age.

Children under age three years generally have no understanding of the meaning of death. They react to the emotions of others around them and often become cranky and irritable. For children of this age, care-givers can help keep routines normal, provide verbal and physical affection and reassurance, and make an effort to cope in healthy ways with their own grief.

Pre-school children between the ages of three and six years often think death is reversible, like going to sleep, and that the deceased person will return. They may believe that their thoughts or actions caused the death and that their thoughts and actions can bring the person back to life. When the person does not return, they may feel they are being punished for not being good enough. Preschoolers may ask the same questions repeatedly in an effort to make sense of death. Likewise, in an effort to understand, they may connect events that are not logically connected. Children of this age are very affected by the emotions of the people around them.

Caregivers can help pre-schoolers cope with loss by maintaining routines. Young children can show grief for only short periods, and may escape into play. Play opportunities, and opportunities to draw and talk about their fears and uncertainties are helpful. Children need to understand the physical reality of death, even if they do not understand the emotional or spiritual aspects, and need to be reassured that they are not responsible for the death. Under the stress of coping with death, many children become more aggressive, irritable, and revert to behaviors more typical of younger children. For instance, toilet-trained children may revert to wetting their pants, or children who have been dressing themselves may insist that they cannot get dressed without help. Although it may be difficult to be patient with these behaviors, they are perfectly normal.

As children progress through elementary school, they begin to grasp the finality of death. They may fear that death is contagious and worry that other people close to them will also be taken away. They may still blame themselves for causing the death. Some children become fascinated with the physical processes involved in death and dying and ask many questions related to the disposal of the body. Children this age still have difficulty understanding spiritual and religious concepts related to death. Like younger children, elementary age children may become more aggressive, have difficulty sleeping, develop problems in school and with social behavior, and develop unnatural fears or phobias related to death.

Caregivers can help by honestly addressing childrens questions, fears, bad dreams, and irrational thoughts. Children of this age are not satisfied with cliches like dont worry or everything will be all right. They benefit from a warm, loving, consistent environment and the opportunity to talk, draw, and play out their concerns. They often seek specific information on why and how a person died in an effort to make sense of death.

Pre-teenagers understand the finality of death and begin to be concerned about how the death will change their world. They often ask few questions, are self-conscious about their fears, and are reluctant to talk about death, although they may show an increased interested in the spiritual aspects of life and death and in religious rituals. Pre-teens are emotionally fragile, and may show their distress with changed behavior, including anger, disrupted relationships with friends, school phobia, difficulty sleeping, and changes in eating patterns.

Providing support for a pre-teen involves encouraging them to express their feelings, if not in spoken words, then in drawing, writing, or music. Many pre-teens act out and become aggressive. They need help in understanding and identifying their feelings and channeling their emotions into productive activities. Many pre-teens regress to behaviors of younger children, while some try to assume adult responsibilities. A warm, loving, open, stable environment helps them weather their emotional storms.

Teenagers experience death in basically the same ways as adults. They see death as an interruption in their lives and as the enemy. They may react in wildly emotional ways or show almost no reaction at all. Most teens prefer to grieve with their friends, rather than with adults. They may romanticize death and obsess about it. Many question their spiritual values and religious beliefs. It is common for teens that experience the death of someone close to them to engage in risky behaviors, such as drive cars fast, use alcohol or drugs, become sexually irresponsible, and refuse to make plans. Many teens are angry and have suicidal thoughts. Others simply close themselves off and refuse to think about the death. Many teens also have changes in their sleeping and eating patterns and show poorer physical health after the death of some one close to them.

Teens can be helped by being guided to a trusted adult (not necessarily a family member) who will listen to them and give them permission to grieve. They need to be guided away from risky behaviors and toward impulse control. When they will talk about their feelings, they need adults who will be good listeners, who will accept their feelings as valid, and answer their questions honestly, even if that involves saying I dont know the answer. Teens will probably regress to younger behavior patterns, and need to be relieved of the burden of adult responsibilities when possible.

Adults experiencing a death feel a whole range of emotions including panic, shock, disbelief, hopelessness, irritability, isolation, and sometimes even relief if the death comes after a long, painful, lingering illness. They need time to go through different stages of grief. Just as with teens, adults may become depressed, and their physical and mental health may suffer. They also may worry about the practical effects the death will have on their life. For example, their financial security may change. Having friends who are good listeners and who offer practical help when needed can ease


Gerontology The scientific study of aging with regard to its social, physical, and psychological aspects.

Life span The duration of life.

adults through difficult emotional times. Many people, both children and adults, find short term professional counseling and grief support groups helpful in understanding their emotions and knowing that they are not going through the grief process alone.

After death, virtually all religions and cultures perform some ceremony to mark the death and celebrate the life and memories of the person who has died. There ceremonies and rituals are important to the survivors. Occasionally before a funeral can occur, an autopsy must be done to determine precisely the cause of death. Autopsies are usually performed in the event of an unexpected death or a suspected criminal activity. The idea of an autopsy may be very disturbing to the survivors.

During an autopsy, a specialist medical doctor called a pathologist examines the body and submits a detailed report on the cause of death. Although an autopsy can do nothing for the individual after death, the information it provides can benefit the family and, in some cases, medical science. For example, the link between smoking and lung cancer was confirmed from data gathered through autopsy.

Some people seek to thwart aging and death through technologies such as the transplantation of organs, cosmetic surgery, and cryopreservation (deepfreezing) of the recently deceased in the hope that a future society will have found the means to revitalize the body and sustain life.

See also Artificial heart and heart valve; Autoimmune disorders; Cell death; Cryobiology; Stress, ecological.



Bowker, Lesley. Oxford Handbook of Geriatric Medicine. Oxford, UK, and New York: Oxford University Press, 2006.

Hazzard, William R., ed. Principles of Geriatric Medicine and Gerontology. 5th ed. New York: McGraw-Hill Professional, 2003.

Kane, Robert L. Essentials of Clinical Geriatrics. New York: McGraw-Hill, 2004.


National Institute on Aging (NLA). Leading the Federal Effort on Aging Research. <> (accessed November 27, 2006).

United States Department of Health and Human Services Administration on Aging (AOA). Home page of AOA. <> (accessed November 27, 2006).

Louise Dickerson

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Aging and death

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