Theories of aging

THEORIES OF AGING

1. Theories of Aging Dr. Ramandeep Kaur Saini (PT) Assistant Professor-Community Physiotherapy DPO’s NETT College of Physiotherapy

2. Objectives : At the end of this session you will be able to- Define aging Identify different theories of aging Describe the theories of aging using biological and non-biological perspective

3. What is aging? Aging is the accumulation of changes in an organism overtime or latter part of animate life. Multidimensional process

4. What is aging? Aging is the deterioration of a mature organism resulting from time dependent, essentially irreversible changes intrinsic to all members of the species such that with the passage of time they become increasingly unable to cope with stresses of environment, thereby increasing the probability of death. (Handler)

5. Types of aging Biological Psychological Functional Social Reference: Pathath A W (2017), Theories of Aging, International Journal of Indian Psychology, Volume 4, (3)

6. Theories of aging: types

7. Biological aging Age associated changes that involve physical structure and functioning of body affecting persons ability to function or survive. Regulated by 2 factors- a genetic component - environmental and lifestyle component Biological aging theories: Stochastic Non Stochastic

8. Foci of Biological 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 Reference: Madison, H.E. (2002).“Theories of Aging”. In Lueckenotte , A.G. (ed), Gerontologic Nursing.  St. Louis: Mosby . 

9. STOCHASTIC THEORIES NON-STOCHASTIC THEORIES FREE RADICAL PROGRAMMMED ERROR/ORGEL GENE/BIOLOGICAL CLOCK WEAR AND TEAR NON-ENDOCRINE CROSS LINKAGE THEORY IMMUNOLOGICAL WASTE ACCUMUATION THEORY SOMATIC MUTATION THEORY Biological aging

10. Stochastic theories- Free radical theory Oxidation of protein, fat, & carbohydrate results in free radical formation. This theory suggest that highly reactive by-product of oxidative metabolism can react with cellular constituent including proteins, DNA, lipids, to generate long-lived dysfunctional molecules that interfere with cellular function. Plasma membrane damage by free radical which is essential for homeostasis.

11. Free Radical Theory- Effect on cellular components

12. Error theory Over time, cells accumulate errors in their DNA and RNA protein synthesis that cause the cells to die (Orgel, 1970). Environmental agents and randomly induced events can cause error, with ultimate cellular changes. Aging would not occur if destructive factors did not exist and cause ‘errors’ such as mutations and regulatory disorders. Example- Large amounts of X-ray radiation, UV radiation cause chromosomal abnormalities.

13. Wear and tear theory The daily grind of life, in particular abuse or overuse, literally wears the body out, leading to disease states. Example- The degeneration of cartilage and eventual grinding of bone on bone causes aging process, as wear and tear exceeds the body’s ability to repair. Cells in heart muscle, neurons, striated muscle, and the brain cannot replace themselves after they are destroyed by wear and tear. Studies of people with osteoarthritis suggest that cartilage cells age over time, and this degeneration is not due solely to strenuous exercise but also to general wear and tear. These studies point out that aged cells have lost the ability to counteract mechanical, inflammatory, and other injuries due to their senescence (Aigner, Rose, Martin, & Buckwalter, 2004).

14. Cross linkage theory Over time, biochemical processes create connections between structures not normally connected. With age, collage is less soluble, rigid and cross-linked. Molecular cross linking between protein molecules such as collagen found in skin, tendons & ligaments and the glycation (cross linking) of other structural proteins & lipids(fats) with excess glucose disrupts the functions of these molecules, leading to acceleration of ageing process. Example- Elastin dries up and cracks with age. Hence skin with less elastin tends to be drier and wrinkled. Over time, because of decreased extracellular fluid, numerous deposits of sodium, chloride, and calcium build up in the cardiovascular system.

15. Waste accumulation theory The somatic mutation theory of aging

16. Non stochastic: Programmed theory The Hayflick phenomenon suggests that cells divide until they can no longer divide, whereupon the cell’s infrastructure recognizes this inability to further divide and triggers the apoptosis sequence or death of the cell. Human cells age each time they replicate because of the shortening of the telomere. Example- Increased cell apoptosis rates cause organ dysfunction, and this is hypothesized to be the underlying basis of the pathophysiology of multiple organ dysfunction syndrome.

17. Gene / Biological clock theory Each cell, or perhaps the entire organism, has a genetically programmed aging code that is stored in the organism’s DNA. Slagboom and associates describe this theory as comprising genetic influences that predict physical condition, occurrence of disease, cause and age of death, and other factors that contribute to longevity. Example- everyday rhythm of the cycle of sleep–wake cycle intervals is part of a time-keeping framework created by an internal clock of body. Its thought that biological rhythm lose some rhythmicity with aging. Because of the linkage with the hypothalamus, autonomic nervous system, and brain stem reticular formation, diurnal changes in metabolism, body temperature, and heart rate and blood pressure occurs.

18. Neuroendocrine theory This theory describes a change in hormone secretion. When the stimulating and releasing hormones of the pituitary and the hypothalamus are out of synch with the endocrine glands, an increase in disease is expected in multiple organs and systems Examples- Decreased estrogen causes the thinning of bones in older women. Growth hormone is part of the process that increases bone and muscle strength. GH stimulated the release of insulin like growth factor produced by liver. Melatonin is produced by the pineal gland and is thought to be responsible for coordinating seasonal adaptations in the body. There is a higher chance of excess or loss of glucocorticoids, aldosterone, androgens, thyroxine, and parathyroid hormone when the hypothalamus pituitary- endocrine gland feedback system is altered.

19. Immunological theory Describes the normal aging process of humans and animals as being related to faulty immunological function (Effros, 2004). Example- Decreased immune function in the elderly due to the thymus gland shrinking to 15% of its capacity, Altered lymphocyte function-T cell differentiation lost with aging Decreased cell mediated and humoral immune response

20. Summary of biological theories:

21. Sociological theories of aging Activity theory Disengagement theory Selectivity theory Subculture theory Age stratification theory Continuity theory

22. Activity theory Individuals need to remain active to age successfully. Activity is necessary to maintain life satisfaction and a positive self-concept As role changes, individual finds substitute activity for the same.

23. Disengagement theory Proposed by Cumming and Henry. As individuals age, they withdraw from society, and society encourages this withdrawal. Individuals would change from being centered on society and interacting in the community to being self-centered persons withdrawing from society, by virtue of becoming “old.” Social equilibrium would be the end result.

24. Selectivity theory Mediates between activity and disengagement theory May benefit older people to become more active in some aspects of their lives while more disengaged in others.

25. Continuity theory Atchley’s theory that in later life the elders make adaptations to enable them to gain a sense of continuity between past and present. Inclined to maintain habits, personalities and life-styles Contributes to well being

26. Subculture Older adults form a unique subculture within society to defend against society’s negative attitude towards aging and accompanying loss in status. Social status determined by health and mobility (Rose,1965)

27. Age stratification Rileys and colleagues observed that society is stratified into different age categories that are the basis for acquiring resources, roles, status and deference from others in society. People born in same cohort has same ideologies, experiences, attitudes and values as well as expectations regarding the timing of life transitions. Thus, there is a high degree of interdependence between older adults & society

28. Summary of social theories:

29. Psychological theories Human needs Individualism Life span Stages of personality development

30. Human needs Maslow--1954 Each individual has an innate internal hierarchy of needs that motivates all human behaviors. depicted as a pyramid; the ideal is to achieve self-actualization, having met all the “lower” level needs successful .

31. Individualism Jung's theory,1960 Our personality develops over a life time and is composed of an ego or self identity that has personal and collective unconsciousness. As individual age, they begin to reflect on their beliefs and life accomplishments. One age successfully when he or she accepts the past, adapts to physical decline and cope with the loss of significant others.

32. Life course Life stages are predictable and structured by roles, relationships and values, development and goals. Person adapt to changing roles and relationship. Age-group norms and characteristics are an important part of the life course.

33. Stages of personality development Erikson’s theory 8 sequential stages of personality development Ego integrity versus despair Individual search for meaning of their lives and evaluate accomplishments Older adults face additional challenge or life tasks including physical and mental decline Accepting the care of others and detachment

34. Summary of psychological theories:

35. References Jean Lange,Theories Of Aging. The Gerontological Nursing Competences For Care.2 nd ed. Physiotherapy in Community Health And Rehabilitation, Waqar N. Pathan AW, Theories of Aging, The Int J. Of Indian Psychology,2017. Madison, H.E. (2002).“Theories of Aging”. In Lueckenotte , A.G., Gerontologic Nursing .

36. THANK YOU