Topic two: theories of aging & approaches to long-term health

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Topic Two: Theories of Aging & Long-term Approaches to Health

Dr. Maha Albqoor

Theories of Aging

• Biologic Theories

• Psychosocial Theories

• Nursing Implications

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Biological Theories• Biological theories define aging as an involuntary process that overtime causes

changes in cells and tissue of the body

• Other biological theories explain aging process because of interactions with the environment

Psychosocial Theories Explain

• Why older adults have different responses to the aging process

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Biological Theories of Aging

Genetic theories Non-genetic theories

Gene Immunologic/Autoimmune

Error Free Radicals

Somatic Mutation Wear & Tear

Programmed Cross Link or Collagen

Gene Theory• This theory proposes the existence of one or more harmful genes that activate

overtime, resulting in the typical changes seen with aging and limiting the life span of the individual

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Gene Theory

• To date, evidence in this field remains controversial, and aging should be more

safely considered as a stochastic process, rather than a programmed mechanism

directly governed by genes.

• At least 15 different genetic manipulations inducing life extension in organisms such

as yeast, fruit flies, and mice have been demonstrated

• However, it is still unknown how the proteins coded by these genes are acting in the

regulation of longevity.

• Gene or genome?

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Error Theory

• This theory proposes that errors in ribonucleic acids (RNA) protein synthesis cause errors to occur in cells in the body organs, resulting in a progressive decline in biological function

Somatic Mutation Theory

• This theory proposes that aging results from genetic damage of the DNA which leads

to progressive loss of potential to make necessary proteins

• This damage is caused by the exposure to chemicals and radiation

• This damage also causes chromosomal abnormalities that lead to disease or loss of

function later in life

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Somatic Mutation Theory

• This theory states that an important part of aging is determined by what happens to our genes after we inherit them.

• From the time of conception, our body's cells are continually reproducing. Each time a cell divides, there is a chance that some of the genes will be copied

incorrectly. This is called mutation.• Exposures to toxins, radiation or ultraviolet light can cause mutations in your

body's genes. The body can correct or destroy most of the mutations, but not all of them.

• Eventually, the mutated cells accumulate, copy themselves and cause problems in the body's functioning related to aging.

Programmed Aging Theory

• This Genetic theory believes that individuals inherit a genetic program that determines their life expectancy

• This theory proposes that every person has a “biologic clock” that starts ticking at the time of conception

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Programmed Aging Theory

• As the program plays out, the person experiences changes such as atrophy of the thymus, menopause, skin changes, and graying of hair

• Supporting the genetic theory is the fact that some families have a strong predisposition for longevity

• Identical twins have very similar life expectancies even more similar than the life expectancy among siblings

• Biological clocks act through hormones to control the pace of aging. Recent studies confirm that aging is hormonally regulated and that the evolutionarily conserved insulin/IGF-1 signaling (IIS) pathway plays a key role in the hormonal regulation of aging.

Non-Genetic Theories

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Immunologic Theories

• The immune system is an important defense mechanism of the body that

weakens over time, making an aging person more susceptible to diseases.

• These theories also proposes that the increase in autoimmune diseases and

allergies seen with the aging is caused by changes in the immune system.

• It is well documented that the effectiveness of the immune system peaks at

puberty and gradually declines thereafter with advance in age. For example, as

one grows older, antibodies lose their effectiveness, and fewer new diseases

can be combated effectively by the body, which causes cellular stress and

eventual death

Immunologic Theories

• Dysregulated immune response has been linked to cardiovascular disease,

inflammation, Alzheimer’s disease (AD), and cancer. Although direct causal

relationships have not been established for all these detrimental outcomes, the

immune system has been at least indirectly implicated (4).

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Free Radicals Theory

• Free radicals are unstable atoms called Reactive Oxygen Species (ROS) with excessive energy and capable of damaging the DNA ofmacromolecules, such as nucleic acids, lipids, sugars, and proteins that are susceptible to free radical attack.

• Sources of free radicals:

• 1. produced by the body during the normal processes of respiration and metabolism.

• 2. Following exposure to ultraviolet (UV) and ionizing radiations and chemical pollution.

• Excessive accumulation of free radicals in the body is associated with the physiologic changes of aging and a variety of diseases, such as arthritis, circulatory diseases, diabetes, and atherosclerosis.


• The body does possess some natural antioxidants in the form of enzymes, which help to curb the dangerous build-up of these free radicals, without which cellular death rates would be greatly increased, and subsequent life expectancies would decrease.

• Healthy cells use antioxidants to fight the damaging effects by blocking the chemical reactions which cause free radicals.

• Currently, under investigation are the antioxidant prosperities of vitamins C and E, and pro-vitamin A (beta-carotene).

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• This theory has been boosted by experiments in which rodents fed antioxidants achieved greater mean longevity. However, at present there are some experimental findings which are not agreed with this early proposal.

• A recent research review shows that reactive oxygen species (ROS) signaling is probably the most important enzyme/gene pathway responsible for the development of cell senescence and organismal aging and that ROS signaling might be considered as further development of free radical theory of aging

The Wear and Tear Theory

• This theory presumes that the body is similar to a machine, which loses function when parts wear out.

• Wear and tear/stress response : is a biological stress caused by physical and social changes in humans’ life.

• Weakening of the defense mechanisms associated with the stress response due to aging eventually leads to death.

• This theory also proposes that good health maintenance practices can reduce rates of wear and tear, resulting in longer and better body functioning.

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The Wear and Tear Theory

• Like components of an aging car, parts of the body eventually wear out from repeated use, killing them and then the body.

• The wear and tear theory of aging was first introduced in 1882, it sounds perfectly reasonable to many people even today, because this is what happens to most familiar things around them.

Crosslink or Connective Tissue Theory (Collagen)

• The cross-linking theory, also referred to as the glycosylation theory of aging, was proposed in 1942.

• According to this theory, an accumulation of cross-linked proteins damages cells and tissues, slowing down bodily processes resulting in aging.

• This results in the skin changes typically attributed to aging, such as dryness, and loss of elasticity.

• Water-insoluble protein fractions increase in the brain cortical tissue and liver of rats during aging in both sexes.

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Crosslink or Connective Tissue Theory (Collagen)

• This suggests a possible increase in the cross-linking of proteins which may be due to the formation of, for example, hydroxyl free radicals during several metabolic processes.

• This irreversible phenomenon was seen in old rats.

• The cross-linked proteins have a very much increased molecular weight, they become mostly insoluble, which makes tissues unable to fight or extract them.

• Living a longer life is going to lead to the increased amounts of cross-linking disorders include senile cataract and the appearance of tough, leathery and yellow skin.

Psycho-social Theories of Aging

• Disengagement Theory

• Life-course Theories

• Continuity Theory

• Activity Theory

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Disengagement theory

• Older people are systematically separated, excluded, or disengaged from society

as a whole.

• Older adults desire to withdraw from society as they age, so the disengagement

is mutually beneficial (i.e. allow the transfer of power to younger generations

and this allows for the maintenance of social equilibrium).

Life-course Theories

• These theories trace personality and personal adjustment throughout a person’s life.

• Here we will discuss three of the most common theories:

• 1. Erickson’s Theory

• 2. Havighurst’s Theory

• 3. Newman’s Thoery

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Erickson’s Theory

Psycho-social Theories of Aging

Disengagement Theory


Continuity Theory

Activity Theory

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These theories trace personality and personal adjustment throughout a person’s life.

Here we will discuss three of the most common theories:

1. Erickson’s Theory

2. Havighurst’s Theory

3. Newman’s Theory

Erickson’s Theory

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Havighurst”s Developmental Tasks of Aging

Havighurst proposed a bio psychosocial model of development, wherein the

developmental tasks at each stage are influenced by an individual’s biology

(physiological maturation and genetic makeup), his psychology (personal values

and goals), as well as his sociology (specific culture to which the individual

belongs).


Later Maturity – over 60 years: defines specific tasks for late life as:

Adjusting to decreasing physical strength and health

Adjusting to retirement and reduced income

Adjusting to death of spouse

Establishing a relationship with one’s age group

Adapting to social roles in a flexible way

Establishing satisfactory living arrangements

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Infancy and Early Childhood – birth to 5 years

Learning to walk

Learning to control bodily wastes

Learning to talk

Learning to form relationships with family members

Middle Childhood – 6 – 12 years

Learning physical skills for playing games

Developing school-related skills such as reading , writing, and counting

Developing conscience and values

Attaining independence


Adolescence – 13 – 17 yearsEstablishing emotional independence from parentsEquipping self with skills needed for productive occupationAchieving gender-based social roleEstablishing mature relationships with peers of both sexesEarly Adulthood – 18 – 35 yearsChoosing a partnerEstablishing a familyManaging a homeEstablishing a career

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Middle Age – 36 – 60 years

Maintaining economic standard of living

Performing civic and social responsibilities

Relating to spouse as a person

Adjusting to physiological changes

Newman’s Theory

Coping with the physical changes of aging

Redirecting energy to new activities and roles, including retirement, grand parenting, and widowhood.

Accepting one’s life

Developing a point of view about death

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Activity Theory

The activity theory occurs when individuals engage in a full day of activities and maintain a level of productivity to age successfully.

The activity theory basically says: the more you do, the better you will age. People who remain active and engaged tend to be happier, healthier, and more in touch with what is going on around them.

The activity theory was first used by elderly program designers , who worked on scheduling work and tasks of elderly people.

The theory was criticized that it fails to consider maintenance of one's mid-life or changes that are made when entering retired or older life.

Activity TheoryIn the activity theory perspective, there is an assumption that activity is

vital to well-being. Stress is placed on the importance of older people being dynamic and active participants in the world around them.

According to this concept, the successful achievement of each task leads to happiness and better chances of success with later tasks. It is assumed in this theory that all older people have the same psychological and social needs and preferences.

This theory emphasizes that well-being and life satisfaction, defined as ‘successful ageing’, are reflected in old age by the extent to which the individual is able to remain involved in the social context, e.g. to maintain social roles and relationships.

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Activity Theory

The theory is based on the belief that one’s self-concept is affirmed though activities associated with various forms of role support. As losses occur that are associated with ageing, they should be replaced with new and different roles, interests or people.

Purposeful activities and interactions that promote self-esteem improve the overall satisfaction with life or event at on older age.

Continuity Theory

According to this theory, the latter part of life is a continuation of the earlier part and therefore an integral component of the entire life cycle. When viewed from this perspective, the theory can be seen as a developmental theory.

The theory proposes that older age try to maintain or continue previous habits, preferences, commitments, values, and beliefs.

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Continuity Theory

• The continuity theory states that an individual develops habits and preferences and

other dispositions during the process of becoming adult and that these become

connected with the personality. As adults strive to achieve their goals, their past

experiences, decisions and behaviors will form the foundation for their present and

future decisions and behaviors

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Continuity Theory

The basic principle of the continuity theory is that, as middle-aged and elderly adults

adapt to changes associated with the normal ageing process, they will attempt to

rely on existing resources and comfortable coping strategies.

Continuity Theory

Continuity of self occurs in two domains: internal and external.

Internal continuity occurs when one wants to preserve some aspects of oneself from the past so that the past is sustaining and supporting one’s new self.

External continuity involves maintaining social relationships, roles and environments.

To the extent that internal and external continuity are maintained, life satisfaction is high. The personality and basic patterns of behavior are said to remain unchanged as the individual ages.

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Implications for Nursing

By understanding the biological and psychosocial theories of aging, nurses can

recognize problems and provide nursing interventions that will help aging

individuals successfully meet the developmental tasks.

Also help individuals achieve the longest, healthiest lives possible by promoting

health-maintenance practices, and a healthy environment.


It is of value for nurses to be familiar with different theories of ageing and to learn about different perspectives on ageing. Through such knowledge they can become aware of the perspectives they are using and choose to use new ones. But it is not reasonable to expect each individual staff member to be able to determine how a theory could be used in practice.

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Theories of ageing can give nurses more knowledge about different views on ageing.

However, they do not give instructions on how to put theory into practice.

It is important to ‘translate’ theories into guidelines that can be used in practice.

Further studies could involve investigating whether and how the psychosocial

theories of ageing have been used in nursing. Further, it may be possible to derive

practical gerontological nursing models from all the ageing theories.

Long Term Approaches to Health

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Long Term Approaches to Health

• Nutritional Status in Childhood and Height

• Family Composition

• Childhood Socioeconomic Conditions

• Urban vs. Rural Place Living

• Socioeconomic Conditions among African Americans

• Inflammatory Exposure and Chronic Diseases

• Fetal Life Predictors

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Nutritional Status in Childhood

• Retrospective studies (had to rely on retrospective reports) revealed a

positive association between poor nutritional status and old-age mortality

• Arm length exhibits a significant negative association with old-age mortality.

Specifically, a log unit (cm) increase in arm length corresponds to a 22

percentage point decrease in the mortality hazard

(Huang & Elo, 2009)

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Height

The most important influences on height are nutritional intake and infection in childhood

• Of course, there is also a genetic component to height that introduces noise into the relationship

• studies that have controlled for adult socioeconomic status have demonstrated an independent effect of height on adult mortality, particularly on deaths due to cardiovascular diseases.

(Preston et al., 1992)

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Height

Waaler (1984): examined the relation between height and mortality among 1.7 million

Norwegians. The risks of death at age 40-59 for men who were 165 cm (65.0 inches)

was 71% higher than for men who were 182.5 cm (71.9 inches).

The relationship was especially marked for cardiovascular diseases, tuberculosis, and

chronic obstructive lung disease. It was essentially absent for cancer and accidents.

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Family Composition

Measured by the sex-composition: (Single child, multiple children of mixed sex, multiple children of single sex)

Results:

• Sibling sex-composition is a significant predictor of old-age mortality(Huang & Elo, 2009)

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Family Composition

• Men who grew up with only brothers experience a significantly higher risk of death than men who grew up with both brothers and sisters or women who grew up with only sisters.

• Women benefited most from growing up with only sisters as they experience the lowest risk of death at ages 80 and above.

• Men and women with no siblings faced a higher risk of death at ages 80 and above than their counterparts in families with both sons and daughters.

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Childhood Socioeconomic Status

• Disadvantaged socioeconomic environment in childhood increases the risk of adulthood mortality (indirect positive mechanism)

• Childhood SES, measured by father’s occupation, is a significant predictor of old-age mortality

• Respondents whose fathers were employed in professional or administrative and non-agricultural occupations have a somewhat lower risk of death than those whose fathers were employed in agriculture

(Huang & Elo, 2009)

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Urban vs. Rural Place Living

• Huang & Elo: Until the early 20th century, living in a city was associated with

higher risk of mortality (before urban sanitary improvements)

• Preston et al.: The most plausible interpretation of the urban mortality

disadvantage before the deployment of effective public health measures is the

greater density of habitation and sharing of common resources such as water

supplies that facilitated the spread of communicable diseases.

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Urban vs. Rural Place Living

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Socioeconomic Conditions among African Americans

• Investigated the association between social and economic conditions in childhood and the probability of surviving to age 85 among African Americans

• Above age 45 about 64% of deaths occurred

• Only about 12.3% survived to age 85

(Preston et al., 1992)• Tables show Preston et al. findings:

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Inflammatory Exposure

• Inflammatory diseases associated with higher levels of CRP such as chronic tuberculosis, diarrheas, peptic ulcers, and periodontal disease

• Among Americans currently in their 50s, those who experienced major childhood illness are 15% more likely to report having cardiovascular conditions and twice as likely to have cancer or chronic lung conditions

• Declining infection during the 20th century has been estimated to explain 11 to 24% of the reduction in late-life morbidity and mortality

(Finch & Crimmins, 2004)

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Respiratory Tuberculosis (TB)

• During the 19th and early 20th centuries, respiratory TB was one of the leading causes of death in the developed world

• Now TB appears to be one of the most opportunistic infections associated with AIDS and remains an important public health problem and a major cause of preventable adult deaths in some developing countries

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Hepatitis B, Liver Cirrhosis, and Liver Cancer

• HBV PHC LC: much more likely if the primary infection occurs in early childhood

• This pattern demonstrates a very high death rate at older ages (30+) in Asia and Africa (Taiwan, Korea, Hong Kong, and Singapore)

• Primarily among males (alcohol consumption)

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Rheumatic Heart Disease

• Recurrent attacks of streptococcal upper respiratory tract infection lead to ARF and RHD, then damage to heart valves

• In developed countries, ARF and RHD have declined substantially during the 20th

century

• In developing countries, the prevalence is substantially above that in developed countries, but it varies considerably among countries.

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CVDs

• Fetal life: A history of growth retardation during the fetal period might lead to high blood pressure in later life

(Gennser et al., 1988)

• Childhood: By 10 years of age, developing fatty streaks which are considered as the precursor arterial lesions can evolve into the advanced form of atherosclerosis (progression of atherosclerosis may begin in childhood)

(Ross, 1988)

• Adolescence: Individuals who were most obese at age 18 suffered mortality from CVD at 3.5 times the rate of men in the optimal range

(Hoffmans et al., 1989)

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Chronic Obstructive Lung Disease & Respiratory Infections

• Chronic obstructive lung disease progressively deteriorates the lung function and can becoming disabling or fatal by middle age

• Indoor and outdoor air pollution are potential exacerbating factors

(Samet et al., 1983; Bumgarner and Speizer, 1989).

• Lower respiratory tract infections in childhood may aid in the development of chronic obstructive lung disease in later life

• EBV, H pylori, HPV, etc.(Samet et al., 1983)

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Fetal Life Predictors

• Reviewed epidemiologic data and data from extensive clinical and experimental studies that indicated that early life events play a powerful role in influencing later susceptibility to certain chronic diseases

• Slow growth in utero may be associated with increased allocation of nutrients to adipose tissue and may then result in accelerated weight gain during childhood which may contribute to a higher risk of CHD, HTN, and DM2

(Gluckman et al., 2008)

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Topic two: theories of aging & approaches to long-term health

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