THEORIES OF AGING

Based on information in: Madison, H.E. (2002).“Theories of Aging”. In Lueckenotte, A.G. (ed), Gerontologic Nursing. St. Louis: Mosby.

Theories of Aging:attempt to explain the phenomenon of aging

as it occurs over the lifespan

– aging is viewed as a total process that begins at conception

– senescence: a change in the behavior of an organism with age leading to a decreased power of survival and adjustment

Theories of Aging: Types

Biologic

Sociologic

Psychologic

Moral/Spiritual

Biologic Theories:

Concerned with answering basic questions regarding the physiological processes that occur in all living organisms as they chronologically age

Foci of Biologic Theories

Explanations of:– 1) deleterious effects leading to decreasing

function of the organism

– 2) gradually occurring age-related changes that are progressive over time

– 3) intrinsic changes that can affect all member of a species because of chronologic age

ALSO:– all organs in any one organism do not age at

the same rate

– any single organ does not necessarily age at the same rate in difference individuals of the same species

Biologic Theories: Divisions

Stochastic: Explain aging as events that occur randomly and accumulate over time

Nonstochastic: View aging as certain predetermined, timed phenomena

Stochastic Theories

Error Theory Free Radical Theory

Cross-Linkage Theory

Wear & Tear Theory

Error Theory

Originally proposed in 1963Basis: 1)errors can occur in the transcription

in any step of the protein synthesis of DNA– 2) error causes the reproduction of an enzyme

or protein that is not an exact copy– 3) As transcription errors to occur, the end

product would not even resemble the original cell, thereby compromising its functional ability

Error, cont’d

More recently the theory has not been supported by research– not all aged cells contain altered or

misspecified proteins

– nor is aging automatically or necessarily accelerated if misspecified proteins or enzymes are introduced into a cell

Free Radical TheoryFree radicals are byproducts of

metabolism--can increase as a result of environmental pollutants

When they accumulate, they damage cell membrane, decreasing its efficiency

The body produces antioxidants that scavenge the free radicals

Free Rads, cont’d

In animal studies, administration of antioxidants postpones the appearance of diseases such as cardiovascular disease and CA

Free radicals are also implicated in the development of plaques associated with Alzheimer’s

Cross-Linkage Theory

Some proteins in the body become cross-linked, thereby not allowing for normal metabolic activities

Waste products accumulate

Result: tissues do not function at optimal efficiency

C-L Theory, cont’d

Some research supports a combination of exercise and dietary restrictions in helping to inhibit the cross-linkage process

Wear & Tear Theory

Proposed first in 1882

Cells simply wear out over time because of continued use--rather like a machine

Would seem to be refuted by the fact that exercise in OA’s actually makes them MORE functional, not less

Nonstochastic Theories:

Programmed Theory

Immunity Theory

Programmed (Hayflick Limit) Theory

Based on lab experiments on fetal fibroblastic cells and their reproductive capabilities in 1961

Cells can only reproduce themselves a limited number of times.

Life expectancies are seen as preprogrammed within a species-specific range

Immunity Theory

Immunosenescence: Age-related functional diminution of the immune system

Lower rate of T-lymphocyte (“killer cells”) proliferation in response to a stimulus

& therefore a decrease in the body’s defense against foreign pathogens

Immunity, cont’d

Change include a decrease in humoral immune response, often predisposing older adults to:– 1)decreased resistance to a tumor cell challenge

and the development of cancer– 2) decreased ability to initiate the immune process

and mobilize defenses in aggressively attaching pathogens

– 3) increased susceptibility to auto-immune diseases

EMERGING THEORIES OF AGING

Neuroendocrine Control (Pacemaker) Theory

Metabolic Theory/Caloric Restriction

DNA-Related Research

Neuroendocrine Control

“…examines the interrelated role of the neurologic and endocrine systems over the life-span of an individual”. (p. 24)

there is a decline, or even cessation, in many of the components of the neuroendocrine system over the lifespan

Neuro, cont’d

Research has shown– 1) the female reproductive system is controlled

by the hypothalamus. What are the mechanisms that trigger changes?

– 2) adrenal glands’ DHEA hormone– 3) melatonin (from pineal gland)--a regulator

of biologic rhythms and a powerful antioxidant. Declines sharply from just after puberty

Metobolic Theory of Aging (Caloric Restriction)

“…proposes that all organisms have a finite amount of metabolic lifetime and that organisms with a higher metabolic rate have a shorter lifespan”. (p. 24)

Rodent-based research has demonstrated that caloric restriction increases the lifespan and delays the onset of age-dependent diseases

DNA-Related Research

Major Developments:

– Mapping the human genome (“…there may be as many as 200 genes responsible for contolling aging in humans”)

– Discovery of telomeres

SOCIOLOGIC THEORIES OF AGING

Disengagement TheoryActivity/Developmental Task Theory

Continuity TheoryAge Stratification Theory

Person-Environment Fit Theory

Changing FOCUS of Sociological considerations of aging:– 60’s focus on losses and adaptation to them– 70’s broader global, societal, and structural

factors influencing lives of OA’s– 80’s-90’s exploration of interrelationships

between OA’s and their physical, political, environmental & socioeconomic mileau

Disengagement Theory

Cumming & Henry--1961Aging seen as a developmental task in and

of itself, with its own norms & appropriate patterns of behavior

“appropriate” behavior patterns involved a mutual agreement between OA’s and society on a reciprocal withdrawal.

No longer supported

Activity Theory (Developmental Task Theory)

Havighurst, Neugarten, Tobin ~1963

“Activity is viewed by this theory as necessary to maintain a person’s life satisfaction and a positive self-concept”. (p.27)

Activity, cont’d

Theory based on assumptions:– 1) it’s better to be active than inactive

– 2) it is better to be happy than unhappy

– 3) an older individual is the best judge of his or her own success in achieving the first two assumptions

Continuity Theory

How a person has been throughout life is how that person will continue through the remainder of life

Old age is not a separate phase of life, but rather a continuation and thus an integral component

Age Stratification Theory

Riley--1985Society consists of groups of cohorts that age

collectivelyThe people & Roles in these cohorts change &

influence each other, as does society at largeThus, there is a high degree of

interdependence between older adults & society

Person-Environment Fit Theory

Lawton, 1982Individuals have personal competencies

that assist in dealing with the environment:– ego strength– level of motor skills– individual biologic health– cognitive & sensory-perceptual capacities

P-E Fit, cont’d

As a person ages, there may be changes in competencies & these changes alter the ability to interrelate with the environment

Significant implications in a society that is characterized by constantly changing technology

PSYCHOLOGIC THEORIES OF AGING

Maslow’s Hierarchy of Human Needs

Jung’s Theory of Individualism

Erikson’s Eight Stages of Life

Peck’s Expansion of Erikson’s Theory Selective Optimization with Compensation

Maslow’s Hierarchy of Human Needs

Maslow--1954“…each individual has an innate internal

hierarchy of needs that motivates all human behaviors”. (p. 29

depicted as a pyramid; the ideal is to achieve self-actualization, having met all the “lower” level needs successful

“Maslow’s fully developed, self-actualized person displays high levels of all of the following characteristics: perception of reality; acceptance of self, others, and nature; spontaneity; problem-solving ability; self-direction; detachment and the desire for primacy; freshness of peak experiences; identification with other human beings;…….

…satisfying and changing relationships with other people; a democratic character structure; creativity; and a sense of values.

Only about 1% of us are truly ideal self-actualized persons

Jung’s Theory of Individualism

Carl Jung--1960origins are FreudianSelf-realization is the goal of personality

developmentas individual ages, each is capable of

transforming into a more spiritual being

Erikson’s Eight Stages of Life

1993Stages throughout the life course. Each

represents a crisis to be resolved.For OA’s:

– 40 to 65 (middle adulthood): generativity versus self-absorption or stagnation

– 65 to death (older adulthood): ego integrity versus despair

Erikson, cont’d

“Self-absorbed adults will be preoccupied with their personal well-being and material gains. Preoccupation with self leads to stagnation of life”

“Unsuccessful resolution of the last crisis may result in a sense of despair in which individuals view life as a series of misfortunes, disappointments, and failures”. (p.30)

Peck’s Expansion of Erikson’s Theory

Erikson’s last two stages are expanded to 7The final three of the developmental tasks

for old age:– ego differentiation versus work role

preoccupation– body transcendence versus body

preoccupation– ego transcendence versus ego preoccupation

Selective Optimization with Compensation

Baltes--1987

Individuals develop strategies to manage losses of function that occur over time

Selective Optimization, cont’d

3 Interacting Elements:– selection: increasing restriction of one’s life to

fewer domains of functioning– optimization: people engage in behaviors to

enrich their lives– compensation:developing suitable, alternative

adaptations

THE END!

Thanks for hanging in there!