Why Do We Age?

Stooped posture, white hair, wrinkled skin, slowed movement, loss of vigor and vitality. What causes them?

Allan Magie, Ph.D., is an associate professor of environmental health, School of Health, Loma Linda University,
Loma, Linda, California.


OLD AGE. Most of us don't want to think about it until we find ourselves suddenly to have arrived. We attempt to delay its emergence through behavior reversion and the use of various potions. But painted-on expressions and flashy clothes can't regenerate the decrepit substructure.

The psalmist declares: "The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away" (Ps. 90:10).

Seventy years. Not very much time. No match for the onward march of eternity's millennia. Yet, God created man to live forever. He wished to enjoy man's unbroken fellowship through the eons of time. But death became an interloper in this relationship.

What images flash across your mind when the words old person, are mentioned? Stooped posture? White hair? Wrinkled and distorted facial and body skin? Slowed movement and gait? General loss of vigor and vitality? Certainly these are characteristics of the aged, but what happened to cause them?

These features are only the reflection of a number of inner changes in the structure, chemical makeup, and working effectiveness of the body's various organs and their components.

Patterns of age differences appear in various physiological characteristics. Some people maintain excellent function even into advanced old age. Others reach a high point in activity in middle age and then decrease. The most common pattern is a steady but gradual decline in adulthood.

What are some of the specific changes that take place in aging?

1. Blood Chemicals. The chemicals in human blood remain relatively constant with aging. Any changes occurring are as a rule the result of some other condition. This is not surprising. Since the activities of all cells of the body are regulated by the circulating blood, even small alterations may upset the fragile balance, and survival could be threatened. In a resting condition, the glucose level, acidity, protein level, total volume, and levels of various salts are relatively constant at all ages. However, if extra demands are placed on the system, some adjustments in these levels may occur in various age groups.

2. Stomach Acid. Stomach acid in men reaches a peak at about age 40, after slowly rising during sexual maturity and adulthood. It then decreases slowly so that at age 80 the average level is about the same as the average at age 15. In women there is no continued rise during middle age. After reaching a peak at age 20 it remains uniform through life, so by age 80 females' acid level is similar to males'. This may be partly why, after puberty, men have four times as many ulcers as women.

3. Serum Cholesterol. The average level of blood cholesterol continues up ward until the age of 55 to 60, after which gradual reductions occur. Undoubtedly these shifts are influenced by such life-style practices as diet and exercise.

4. Heart and Blood Vessels. The resistance to blood flow in the outer tissues of the body increases progressively throughout life as the vessels become less flexible and cholesterollike deposits accumulate. This increase in resistance requires the heart to work harder to maintain the same flow of blood as in younger life.

5. Lungs. The nonfunctioning area of the lungs (unable to exchange gases actively) increases with age. Although a small increase, this is significant. Gas exchange in the lungs is therefore somewhat less effective in the old than in the young.

These last two mentioned functional areas of the body typify the gradual reduction in performance of many of the body's organ systems.

6. Blood Pressure. Although there has been considerable controversy over the relationship between blood-pressure levels and age, it now seems clear many people have a progressive increase in blood-pressure levels with increasing age, particularly up to age 70. There is some evidence, however, that lifelong habits of prudent living diminish this increase.

7. Other Functions. Some of the physiological functions that show a declining pattern as a person ages are the speed at which a nerve impulse travels, the volume of blood moved with each heartbeat, the amount of blood flowing through the kidneys and the rate it is filtered there, secretion of sex hormones, the body tissue's ability to utilize thyroid hormone, and basal metabolism, which may be related to the previous functional change.

The Ability to Adjust

A primary effect of aging is the loss of functions to adapt easily to varying demands placed on the body. In other words, the reserve capacity (that measure of inherent adjustment potential) in many organ systems does not allow the same rapid recovery at age 60 that they provided at age 25. For instance, although the blood-glucose level of a person at 70 is the same as it was in that individual at 20, a 70-year-old's lowered blood-glucose level requires a much longer period of time to regain a normal level if glucose is artificially administered.

Other organ systems also show a reduced ability to respond. Muscular strength and the speed at which one can move diminishes in old age, as does the ability to adjust to changes in environ mental temperature.

Older individuals are often less effective than younger ones in meeting the challenges of the environment, and they require a longer time to readjust their internal environment after alterations occur.

Clearly, age does not influence all organ systems to the same extent. "The spirit indeed is willing, but the flesh is weak" (Matt. 26:41). A strong mind can be found in a derelict body as well as a deteriorating mind in an athletic body.

Aging doesn't even have a uniform effect on different organ systems in the same individual. Thus, a 70-year-old may have the heart output of the aver age 55-year-old, yet have the kidney function of an 80-year-old. It is these differences in the rate of aging among organ systems that represent the source of many of the medical and sociological problems of older people.

Nor is this the whole story. Aging and disease are not mutually inclusive. The individual himself changes with time in ways that appear to increase his susceptibility to certain diseases.

Basis for Aging

In general, two major factors are thought to be responsible for the aging process—intrinsic, or inherited, factors, and extrinsic, or environmental.

Some of the ways that inherited, or genetic, factors may influence aging are:

1. Gradual decline in the production of a growth factor.

2. Increased production of an aging substance.

3. Cessation of growth and failure to replace cells that are destroyed.

4. Depletion of essential cell components or errors in their function.

5. Accumulation of substances in cells that may be harmful to the normal life processes.

Important environmental factors include:

1. Diseases of all kinds, especially infections caused by viruses, bacteria, fungi, and animal parasites.

2. Injury resulting from chemical, mechanical (physical), and temperature changes.

3. Cumulative effects of radiation, both self-imposed (medical and dental X-rays) and natural (cosmic, et cetera).

4. Man's interaction with his fellow beings and perhaps even his attitudes toward other creatures inhabiting this planet.

Death rates fluctuate at both ends of man's sojourn on earth. Relatively high immediately after birth and during in fancy, they then decline rapidly, reaching their lowest point at puberty (12 to 14 years of age). The rates begin to rise slowly during young adulthood, beginning an ever-escalating pattern after age 30. At this point mortality behaves like compound interest, doubling about every eight years after age 30. If man could retain throughout his lifetime the minimum death rate achieved at puberty, he would live almost one hundred times longer than he now does.

The incidence of many diseases—such as cardiovascular (heart and blood vessel) diseases and cancer—increases with age. These diseases generally take a long time to develop, and thus appear characteristically in older people.

Some have regarded aging changes to be a result of disease, accident, or mental-social events, such as loss of a loved one, financial reversals, or loss of social status. It may be that those who live longest are not necessarily those who have inherited greater physical and mental powers, but those who have learned to cope with the stresses of daily life.

We have many questions about the differential death of parts of our bodies, but not many answers. Why do cells die? How do the basic activities of cells change as the cells or the person ages? Why do some organs lose capacity to function as they age? What factors in early life—physical and psychological—tend to reduce longevity? How do personality, life style, disease, and various environmental influences alter the rate of aging?

For the Christian, however, there is a fundamental answer: "Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned." "For the wages of sin is death" (Rom. 5:12; 6:23).

Obviously, people need to understand early in life what life-style practices contribute to the aging process. Thus, future problems may be avoided. In addition, everyone needs to be informed that there are no anti-aging treatments that can be used without possible serious side effects.

The most effective anti-aging agent is the one Solomon describes: "The fear of the Lord prolongeth days: but the years of the wicked shall be shortened" (Prov. 10:27).

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Allan Magie, Ph.D., is an associate professor of environmental health, School of Health, Loma Linda University,
Loma, Linda, California.

November 1977

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