THEORIES OF AGING

There is no single universally accepted definition of aging. Aging is series of changes that occur over time, contribute to loss of function and ultimately result in the death of a living organism.

BIOLOGIC THEORIES

Biologic theories of aging attempt to explain why the physical changes of aging occur. Researcher try to identify which biologic factors have the greatest influence or longevity.

1. The programmed theory: in this theory each individual has a genetic program specifying an unknown but predetermined number of cells divisions.
2. The rut-out-program theory: proposes that every person has a limited amount of genetic material that will run out over a time.
3. The living theory: this proposes that individuals have a finite numbers of breaths or hearts beats that are used up over a time.
4. The gen theory: proposes that the existence of one or more harmful genes that activate over the time resulting in the typical changes seen with aging and limiting the life span of the individual.
5. The molecular theories: propose that aging is controlled by genetic materials that are encoded to predetermine growth and decline.
6. The error theory: proposes that error in ribonucleic acid, protein synthesis cause errors to occur in cells in the body, resulting in a progressive decline in biologic function.
7. The somatic mutations theory: is similar bus proposes that aging result from deoxyribonucleic acid (DNA) damage causes by exposure to chemical or radiation and that this damage causes chromosomal abnormalities that lead to disease or loss function later in life.
8. The free radical theory: excessive accumulation of free radicals in the body is purported to cause or contribute to the physiologic changes of aging and a variety of diseases.
9. The cross line: also called connective tissue theory: is one variation of the free radical theory.
10. The clinker theory: combines somatic mutation, free radicals, and crosslink theories to suggest that chemicals produced by metabolism accumulate in normal cells and cause damage to body organs such as the muscles, heart, nerves and brain.
11. The neuroendrocrine theory: focuses on the complicated of chemical interactions set off by the hypothalamus in the brain.
12. The immunologic theory: the neurologic theory proposes that aging is a function of changes in the immune system. According to this theory, the immune system weakens over the time making an aging persona more susceptible to disease.

PSYCHOSOCIAL THEORIES

Psychosocial theories of aging do not explain why the physical changes of aging.

1. The disengagement theory: This theory proposed that older people are systematically separated, excluded or disengaged from society because that are not perceived to be benefit to the society as a whole. This theory further proposes that older adults desire to withdraw from society as the age, so the disengagement is mutually beneficial.
2. The activity theory: that activity theory proposes that activity is necessary to successful aging.
3. Life course theories: are perhaps the theories best known to nursing. These trace personality and personal adjustment throughout a person’s life..

• Erikson’s theory identifies 8 stages of developmental tasks than an individual must confront throughout the life span: 1. Trust versus mistrusts. 2. Autonomy versus shame and doubt. 3. Initiative versus guilt. 4. Industry versus inferiority. 5. Identify versus identity confusion. 6. Intimacy versus isolation. 7. Generativity versus stagnation. 8. Integrity versus despair.
• Havighurt’s Theory: details the process of aging and defines specific tasks for late life, including:
• Adjusting to decreased physical strength and health.
• Adjusting to retirement and decreased income.
• Adjusting to the loss of a spouse.
• Establishing relationship with one’s age group.
• Adapting to social roles in a flexible way.
• Establishing satisfactory living arrangements.
• Jung’s theory: proposes that development continues trhougt life by a process of searching, questioning and setting goals that are consistent with the individuals personality.

Céspedes Miranda Ela, Rodríguez Capote Karina, Llópiz Janer Niurka, Cruz Martí Niurys. Un acercamiento a la teoría de los radicales libres y el estrés oxidativo en el envejecimiento. Rev Cubana Invest Bioméd  [revista en la Internet]. 2000  Dic [citado  2013  Abr  08] ;  19(3): 186-190. Disponible en: http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S0864-03002000000300007&lng=es.