theories of aging based on information in: madison, h.e. (2002).“theories of aging”. in...
TRANSCRIPT
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!