THEORIES OF AGING

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 1963 • Basis: 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 Theory • Free 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 Theory • Activity/Developmental Task Theory • Continuity Theory • Age 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--1961 • Aging 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--1985 • Society consists of groups of cohorts that age collectively • The people & Roles in these cohorts change & influence each other, as does society at large • Thus, there is a high degree of interdependence between older adults & society

Person-Environment Fit Theory • Lawton, 1982 • Individuals 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--1960 • origins are Freudian • Self-realization is the goal of personality development • as individual ages, each is capable of transforming into a more spiritual being

Erikson’s Eight Stages of Life • 1993 • Stages 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 7 • The 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!

THEORIES OF AGING