Theories of Aging
- Theory may be defined as a cluster of conclusions in search of a premise.
- The justification for using theory is that it provides anchors for thinking & guidelines for examining data.
- Aging is not merely the passage of time. It is the manifestation of biological events that occur over a span of time. However, there is really no perfect definition of aging.
- The student of aging recognizes that gerontology is the scientific study of the aging process, whereas geriatrics is concerned with the medical problems or older adult.
- The focus of gerontology is on determining answers about the normal aging process rather than the diseases of old age.
The suggested criteria that must be met before an aging theory is accepted is as follows:
- The theory must explain why the losses in physiologic function occur (deleterious).
- The theory must explain why the losses are gradual (progressive).
- The theory must explain why the losses cannot be corrected (intrinsic).
- And the theory must explain why the losses occur in all members of a species (universal).
- Psychologic aging is characterized primarily by behavioral changes.
- Sociologic changes refer to changes that relate to the environmental influences that contribute to and affect aging people.
- Each older person is an individual, and each life experience and each change in a person's environment has an effect on that person.
Psychosocial Perspectives on Aging
- Aging is defined here as the transformation of the human organism after the age of physical maturity so that the probability of survival decreases & it is accompanied by regular transformations in appearance, behavior, experience & social roles.
- Psychosocial aging can be described as a result of the disuse of previously acquired skills, random wear & tear, a change in the ability to adapt due environmental variables, loss of internal & external resources, genetic influences over the life span.
- Social scientists agree that genetics (heredity) is a major factor in determining the length of human life, although environment plays an important role in modifying the expected life span.
- The bottom line of Psychosocial Theory: As people grow older, their behavior changes, their social interactions change, and the activities in which they engage change.
The four Psychosocial Theories we will discuss here are:
- Disengagement theory
- Activity theory
- Life-course theories
- Continuity theory
Refers to an inevitable process in which many of the relationships between a person and other members of society are severed & those remaining are altered in quality.
Withdrawal may be initiated by the aging person or by society, and may be partial or total.
It was observed that older people are less involved with life than they were as younger adults.
As people age they experience greater distance from society & they develop new types of relationships with society.
In America there is evidence that society forces withdrawal on older people whether or not they want it.
Some suggest that this theory does not consider the large number of older people who do not withdraw from society.
This theory is recognized as the 1st formal theory that attempted to explain the process of growing older.
Is another theory that describes the psychosocial aging process.
Activity theory emphasizes the importance of ongoing social activity.
This theory suggests that a person's self-concept is related to the roles held by that person i.e. retiring may not be so harmful if the person actively maintains other roles, such as familial roles, recreational roles, volunteer & community roles.
To maintain a positive sense of self the person must substitute new roles for those that are lost because of age. And studies show that the type of activity does matter, just as it does with younger people.
The Activity Theory makes the following certain assumptions:
- There is an abrupt beginning of old age.
- The process of aging leaves people alone & cut-off.
- People should be encouraged to remain active & develop own-age friends.
- Standards & expectations of middle age should be projected to older age.
- Aging persons should be encouraged to expand & be involved.
One theory we are all very familiar with is Erikson's developmental stages, which here approaches maturity as a process. Within each stage the person faces a crisis or dilemma that the person must resolve to move forward to the next stage, or not resolve which results in incomplete development.
Hanighurst stated that for older people to progress they must meet the following tasks:
- Adjust to declining health & physical strength.
- Adjust to retirement & reduced income.
- Adjust to the death of a spouse or family members.
- Adjust to living arrangements different from what they are accustomed.
- Adjust to pleasures of aging i.e. increased leisure & playing with grandchildren.
A more recent framework used in conducting research following these assumptions:
- Aging occurs from birth to death.
- Aging involves biologic, psychologic & sociologic processes.
- Experiences during aging are shaped by historical factors.
States that older adults try to preserve & maintain internal & external structures by using strategies that maintain continuity. Meaning that older people may seek to use familiar strategies in familiar areas of life.
In later life, adults tend to use continuity as an adaptive strategy to deal with changes that occur during normal aging. Continuity theory has excellent potential for explaining how people adapt to their own aging.
Changes come about as a result of the aging person's reflecting upon past experience & setting goals for the future.
Biologic theories classify aging as genetic (heredity) & nongenetic (wear & tear).
- Genetic theories are the most promising in relation to finding answers about aging.
Error & Fidelity Theory
Ok, we all know an Error is a mistake and Fidelity refers to being faithful… so knowing that we can discuss this theory. Also remember that this occurs over a lifetime.
- How does this theory apply to aging? Normally, we constantly or faithfully produce cells throughout our bodies using our same correct DNA map (or proteins) to do so time & time again. What this theory is saying is that over time an error or mistake occurs in our DNA map (or proteins) and it begins to produce cells that are not correct … it's like going from producing a high quality product to producing a lesser quality product. This deterioration results in aging and eventually over a lifetime, death.
Somatic Mutation Theory
This theory holds that Mutations are those inheritable changes that occur in the cellular DNA. If there is extensive damage to DNA and it is not repaired, then there will probably be an alteration in a genetic sequence. There has been some suggestion related to background radiation of various types.
Suggests that glucose acts a mediator of aging.
Glycation is the nonenzymic reaction between glucose & tissue protein.
Studies conclude that glycation may have profound cumulative effect during a person's life. The negative effects of this process on proteins may be a major contributor to age changes.
The effects of this process may be similar to elevated glucose levels & shorter life spans of diabetics.
Theories of cellular aging
Programmed Cellular Aging Theory
Suggests that aging may be a result of an impairment of the cell in translating necessary RNAs as a result of increased turnoffs of DNA.
In other words, the transcription of these messages into functional proteins may be restricted in older people.
Some segments of DNA become depleted with advancing age, or selected cellular structures seem to change with age so that DNA transcription is restricted.
Aging Pacemaker Theory
Suggests that one cell, or one type of tissue, interferes with cell proliferation, thereby initiating the process of senescence throughout the body.
Some suggest the Thymus as the 'pacemaker' or 'biologic clock.'
Theories of the Organ System
As the body ages the immune system is less able to deal with foreign organisms & increasingly make mistakes by identifying ones own tissues as foreign (thus attacking them).
These altered abilities result in increased susceptibility to disease & to abnormalities that result form autoimmune responses.
Neuroendocrine Control Theory
The neurologic & endocrine systems are major controllers of body activity.
During the human life span there is a 10% decrease in the weight of the brain due to both loss of cells & fluids in the cerebrum.
It is suggested the age related changes in response to hormones may be the result of changes in the receptors for hormones rather than changes in the activity of the endocrine hormones themselves.
This theory suggests that humans might live longer if their body temperatures were just 5 degrees lower than the usual 98.6 because there is a relationship between high metabolism (which increases temperature) and shorter-lived species.
It is also suggest that if humans could attain the lower temperature they would live 20% longer.
Nutrient Deprivation Theory
Purposes that oxygen deprivation leads to senescence of deprived cells.
Also referred to as the 'wear and tear' theory.
- Suggests that as people age they produce age spots that are an accumulation of 'biochemical debris' or waste products. It is believed that these waste products accumulate until they interfere with cellular functioning.
Current Thinking & Old Ideas
- Most biogerontologists believe that several mechanisms are operating at the same time to cause aging. There is probably not a single cause of death but many causes.
- Current thinking includes:
- The 'vital substance' theory - we are all born with a certain amount of vital substance and as it is consumed we age and die.
- The genetic mutation theory - several types of gene mutations are known to occur, some are good and some are harmful.
- The reproduction exhaustion theory - is the idea that there is a burst of reproductive activity then a period of rapid aging followed by death.
Theories Presuming a Preexisting Master Plan
Suggests the presence of a biologic clock governed by a series of chemical events.
That there is programmed cell death
That hormone's accelerate some aging processes and can slow down other processes. The trend is more towards hormones being a possible cause of age changes.
There is also agreement that profound changes occur in the brain as humans age but it is not agreed as to whether or not we lose nerve cells.
Theories Based on Random Events
Such as the 'wear and tear' theory where body tissue becomes worn from use and cannot continuously renew itself.
The rate-of-living theory suggests that rapid expenditure of energy precipitates early aging and slow expenditure results in slower aging.
The waste product accumulation theory suggests that a kind of cellular constipation results if cells accumulate more waste than can be disposed of efficiently.
The cross-linking theory of aging suggest that with age some body proteins become cross-linked and may impede metabolic processes
What is the conclusion of all this?
That none of the theories proposed can claim sufficient evidence to account for the aging effects that are witnessed & experienced in humans.
Bottom line: We do not know why we age.
We do know that longevity has increased and by that the possibility that the aging process has slowed.
The common theme in all the theories here is: Change.
As molecules, cells and organ systems continue to live, they change.
An interesting observation about change: When it is considered in earlier life it is referred to & discussed as development and later in life when change is considered it is referred to as aging.
What are the summarized characteristics of aging?
Increased mortality with increasing age.
Changes in chemical composition of the body.
A broad spectrum of progressive deteriorative changes.
Reduced ability to adapt to environmental changes (probably a major factor).
Becoming increasingly vulnerable to disease.
What are the improvements needed in the area of gerontology?
Experts & researchers need to communicate & collaborate across disciplines, as well as use a uniform common language to enhance communication.
Nurses need to analyze & reduce the complexity of these theories and place emphasis on the quality of life of older adults.
Society must develop a positive view of older adults & their potential within society.
Nurses must see older adults as unique individuals with valuable life experiences & recollections that should be utilized.
Also recognize the losses experienced i.e. physical & social.
Society must change or eliminate stereotypes about older adults.
The End! J