Nancy V. Karp, Ed.D., P.T. nvkarp@gmail.com Theories of Aging Nancy V. Karp, Ed.D., P.T. nvkarp@gmail.com

Objectives This presentation will describe aging from both a biological/physiological and a psychosocial perspective. Biological/physiological theories will be presented in two main categories, program theories and error theories. Psychosocial theories will be discussed in two main categories, full-life theories and mature-life theories.

Ponce De Leon In Search of the Fountain of Youth

Is There a Fountain of Youth?

Is There a Fountain of Youth?

What is Aging? The gradual and spontaneous changes that occur in maturation from infant to young adult. These changes create a normal physiologic decline seen in middle and late adulthood. Changes during puberty Graying of hair

Senescence The process by which a cell looses its ability to divide, grow, and function. This loss of function ultimately ends in death. A degenerative process, only. Has no positive features.

Normal vs. Healthy Aging Normal Aging Diseases & impairments of elderly People age differently Diabetes may be a common disease of adulthood, but is not experienced by all aging adults. Healthy Aging Minimize and preserve function Influenced by lifestyle choices One may have a healthy life until senescence makes life impossible.

Life Expectancy Some Factors Influencing Your Life Expectancy Heredity Disease Processes Medical Treatment Lifestyle Choices Nutrition

Theories of Aging “The link between genes and lifespan is unquestioned. The simple observation that some species live longer than others -- humans longer than dogs, tortoises longer than mice -- is one convincing piece of evidence.” The National Institute on Aging

Theories of Aging All aging begins with genetics Aging changes the biochemical and physiological processes in the body Cell and molecular biologists examine and propose theories to explain the aging process What causes aging? How can you influence aging …prolong life?

The Two Main Aging Theory Categories Programmed Theories Aging has a biological timetable or internal biological clock. Error Theories Aging is a result of internal or external assaults that damage cells or organs so they can no longer function properly. Many theories are a combination of programmed and error theories.

Programmed vs. Error Theories Programmed Theories Programmed Senescence Theory Endocrine Theory Immunology Theory Error Theories Wear and Tear Theory Rate-of-Living Theory Cross-linking Theory Free Radical Theory Error CatastropheTheory Somatic Mutation Theory

Programmed Senescence Theory Endocrine Theory Immunology Theory Programmed Theories Programmed Senescence Theory Endocrine Theory Immunology Theory

Programmed Senescence Theory The result of sequential switching “off” or “on” of specific genes. Example – “Hayflick’s Limits” Fibroblasts removed from umbilical cord & cultured Fibroblasts divide and repeated until ~ 50 divisions Will not divide past this point

Telomeric Theory This is an extension of the “Hayflick Limit.” Telomeres are specialized DNA sequences at the end of chromosomes. They shorten with each cell division. When the telomeres become too short, the cell enters the senescence stage. In the normal process of DNA replication, the end of the chromosome is not copied exactly, which leaves an unreplicated gap.

Telomeric Theory The enzyme, telomerase, fills the gap by attaching bases to the end of the chromosomes. As long as the cells have enough telomerase to do the job, they keep the telomeres long enough to prevent any important information from being lost as they go through each replication. With time, telomerase levels decrease. With decreasing telomerase levels, the telomeres become shorter and shorter.

Telomeric Theory Shortened telomeres are found in: Atherosclerosis Heart disease Hepatitis Cirrhosis

Telomeric Theory and Cancer 90% of cancer cells have been found to possess telomerase. Telomerase prevents the telomere from shortening. This allows the cancer cells to reproduce, resulting in tumor growth. Research areas Measuring telomerase may help detect cancer. Stopping telomerase may fight cancer by causing death of cancer cells. Telomerase may be used to help with wound healing or the immune response.

Endocrine Theory Biological clocks act through hormones to control the pace of aging. Hormones effects growth, metabolism, temperature, inflammation and stress. Examples- Menopause Decreased level of estrogen & progesterone Hot flashes, insomnia

Immunologic Theory A programmed decline in the immune system leads to an increased vulnerability to disease, aging and death Example- Decreased T cells (helper cells) in adults Increased diseases in older adults Increased autoimmune diseases in adults

Error Theories Wear and Tear Theory Error Free Radical Theory Rate-of-Living Theory CatastropheTheory Cross-linking Theory Somatic Mutation Theory

Wear and Tear Theory Years of damage to cells, tissues and organs eventually wears them out, killing both them and the body Example- Wearing out of the skeletal system such as in osteoarthritis Wear and tear can be viewed as a result of aging and not the cause of it.

Rate-of-Living Theory The greater an organism’s basal metabolic rate, the shorter the life span. Free radicals or other metabolic by-products play a role in senesce. Example Animals with the most rapid metabolisms tend to have the shortest lifespans, i.e, birds have a shorter lifespan than humans. Studies examining the relationship between metabolic rates and longevity have produced inconsistent results, limiting the usefulness of this theory.

Cross-Linking Theory The accumulation of cross-linked proteins damages cells and tissue, slowing down bodily processes. Example Non-enzymatic glycosylation reactions occur when glucose molecules attach to proteins causing a chain of chemical reactions resulting in a structural change to the proteins. Loss of flexibility of connective tissue Microvascular changes in arteries

Free Radical Theory During aging, damage produced by free radicals cause cells and organs to stop functioning. A free radical is a molecule with an unpaired, highly reactive electron. One type of very reactive free radical is the oxygen free radical, which may be produced during metabolism or as a result of environmental pollution. Oxygen free radicals are formed in your cells, naturally, during the oxidation of food to water and carbon dioxide.

Free Radical Theory The free radical “grabs” a electron from any molecule it its vicinity. It does this because electrons like to exist in pairs. When it “grabs” an electron from another molecule, it damages the other molecule.

Free Radical Theory Some of the molecules that may be damaged by free radicals are fats, proteins, and DNA (both in the nucleus and in mitochondria). If membrane fats are attacked, then you get the breakdown of the cell membrane. If it is a red blood cell membrane, you get hemolysis. If proteins are attacked, you get the breakdown of proteins, which may result in the loss of biological function and the accumulation of “catastrophic” compounds. If DNA is attacked, you will get a mutation that may cause aging or cancer.

Free Radicals As the free radical (green) attacks the membrane it can release another type free radical (blue).

The free radical (blue) attacks the DNA releasing another Damaged membrane mitochondrion The free radical (blue) attacks the DNA releasing another free radical (purple).

Free Radical Theory Free radicals do not go unchecked. The body has a multi-layed defense system that reacts and detoxifies the damaging radicals. Defenses include: Natural antioxidants in the body, such as bilirubin. Enzymes such as superoxide dismutase (SOD), catalase, & glutathione peroxidase. Dietary antioxidants such as beta carotene, and the vitamins C and E.

Free Radical Theory Under normal conditions, your natural defense mechanisms prevent most of the oxidative damage from occurring. The free radical theory of aging proposes that, little-by-little, small amounts of damage accumulate and contribute to deterioration of tissues and organs.

repaired membrane anti-oxidant molecule damaged DNA The anti-oxidant molecule destroys the damaging free radical. The membrane repairs itself, but the DNA remains damaged, impairing the cells function. In addition, the anti-oxidant molecule now has an unpaired electron and thus becomes a new radical.

Free Radical Theory For example, when Vitamin E “scavenges” free radicals, it becomes a free radical and may be more carcinogenic than the original free radical. This is the reason why taking high doses of vitamin E SUPPLEMENTS appears to INCREASE cancer risk in a person, not decrease cancer risk.

Free Radical Theory Not all free radicals cause damage. You use free radicals as part of your immunological response system. Macrophages engulf bacteria Free radical reactions produced inside the macrophage oxidize and kill bacteria. Question: Does it make any biological sense to try to eliminate all free radicals in your body by taking supplements?

Can This Stop Aging?

Can you delay or stop aging by taking vitamins and other free radical scavengers? There is no evidence-based proof that dietary supplements delay or stop aging. This is a big area of nutrition quackery. BEWARE! Remember, there is a lot of evidence-based proof that taking some supplements INCREASES cancer rate, for example lung cancer. Smokers who take beta-carotene supplements have higher lung cancer rates than smokers not taking these supplements. Therefore, the risk/benefit ratio is in favor of NOT taking SUPPLEMENTS to retard aging.

Catastrophe Theory Any damage to the enzyme systems that synthesize proteins in the body results in faulty protein synthesis. The faulty proteins continue to accumulate in the cell until they reach a level that damages the cells, tissues, and organ When enough damage accumulates, this may result in cell malfunctioning ( aging) leading to death.

Somatic Mutation Genetic mutations occur and accumulate with age in the somatic cell causing the cell to: Deteriorate Malfunction Accumulation of mutations result in : Damage to the DNA The theory states that aging is an imbalance between DNA’s ability to repair itself and accumulating DNA damage. When the damage exceeds the repair, the cell malfunctions and this can lead to senesence.

Psychological Theories of Aging

Psychological Theories of Aging Full-Life Development Theories (Erikson’s Theory will be the only one discussed.) Mature-Life Theories Robert Peck’s Theory The Activity Theory (Neugarten’s Theory will be the only one discussed.) The General Theory of Disengagement

Full-Life Development Theory Eric Erickson was one of the first psychological theorists to develop a personality theory that extends to old age.

Full-Life Development Theory Major Concepts The ego is a positive driving force for development. The ego’s job is to establish and maintain identity. A lack of identify leads to lack of direction and non-productivity. There are stages of personality and ego development.

Full-Life Development Theory Major Concepts The last stages are “Adulthood” & “Late Life Stage.” “Adulthood” is characterized by a struggle between “Generativitiy” and Stagnation. “Generativity” Giving back to society by raising children Being productive at work Being involved in the community Guiding, parenting, and monitoring the next generation

Full-Life Development Theory Major Concepts Stagnation Being unproductive Feeling anger, hurt and self absorption As one becomes mature, there is a struggle between “Ego Integrity” & despair “Ego Integrity” Exploring life as a retired person who is not identified with an occupation Contemplating accomplishment Feeling life is successful

Full-Life Development Theory Despair Feeling guilt about the past Not accomplishing life goals The final pathway: dissatisfied despair depression hopelessness

Mature-Life Theories

Mature-Life Theories Robert Peck The elderly go through three developmental stages to reach full psychosocial development. Stage 1 - Ego Differentiation vs. Work Role Preoccupation Stage 2 - Body Transcendance vs. Body Preoccupation Stage 3 - Ego Transcendance vs. Ego Preoccupation

Stage 1 Ego Differentiation vs. Work Role Preoccupation As a person matures, that person moves from “Work Role Preoccupation” which is a concept that describes defining oneself through work or an occupation. A person finds new meaning and value in his or her life. This process is called “Ego Differentiation.”

Stage 2 Body Transcendance vs. Body Pre-occupation A person either accepts the limitations that accompanies the aging process (Body Transcendance) or dwells on diminishing abilities (Body Pre-occupation).

Stage 3 Ego Transcendance vs. Ego Preoccupation Self-examination occurs. If a person believes his or her life has worth and “life contributions” will live on after death, the person experiences “Ego Transcendence.” Otherwise, the person may feel that he or she has lived a useless life and experience “Ego Preoccupation.”

Mature-Life Theories Neugarten Bernice Neugarten describes tasks that must be accomplished for successful aging. Some of these tasks include: Accepting reality and the imminence of death. Coping with physical illness. Accepting the necessity of being dependent on outside support while still making independent choices that can give satisfaction.

Mature-Life Theories Neugarten A person must remain as active as possible. This falls under the category of “activity theory.”

Mature-Life Theories General Theory of Disengagement This theory is controversial and has these features: Both older people and society mutually withdraw from each other. A person gradually disconnects from other people in anticipation of death. Intrinsic changes in personality occur which allow a person to psychologically withdraw from society’s expectations. Note: This is the opposite of “Activity Theory.”

Summary This presentation has described aging from both a biological/physiological and a psychosocial perspective. Biological/physiological theories are divided into two main categories, program theories and error theories. Psychosocial theories are divided into two main categories, full life theories and mature life theories.

The End