How do we age ?
We know that the aging process begins about the mid- twenties when we stop growing and start ripening. By mid-life we are aware of an assortment of physical losses, abilities and vitality. The changes are subtle for some and dramatic for others. It is natural to want to understand the aging process and if possible to control it.
Getting older and aging is not a straightforward proposition of what will happen to our bodies each succeeding year as we get older. We have a lot of data regarding approximate times of when the body begins to reflect various signs of aging, but there is no comprehensive explanation of the mechanism of aging.
Biology has a lot to do with the changes we notice in how our bodies look and function. Our behavior and our individual psychology are a powerful influence on our experience of getting older.
The aging process is also shaped by social structures that include gender, socioeconomic status, race, age, and cultural context. Experts in diverse scientific disciplines agree that aging is a Bio-Psycho-Social phenomenon.
Aging is a Bio-Psycho-Social Phenomenon
The experts also create hundreds of theories on the causes of aging, read that as attempts to explain aging, in several different scientific approaches. The biological theories are relevant because we want to know how we can remain active and vital into our nineties instead of becoming sickly and frail at age 60. Perhaps the psychology of aging theorists can share the secrets to avoiding memory loss and maintaining high levels of cognitive functioning. Since we are asking, how do we join the group of older adults who still maintain emotionally gratifying lives in spite of suffering losses? Social theories of aging may suggest where we can begin.
There are two camps of biological theories on the aging process that attempt to explain what happens to us physically as we age. One group theorizes that aging is Pre-Programmed. The programmed theories imply that aging follows a biological timetable, perhaps a continuation of the one that regulates childhood growth and development. This regulation would depend on changes in gene expression that affect the systems responsible for maintenance, repair and defense responses. Their theories include the Cellular Clock theory, the Neuroendocrine theory, and the Immunological theory.
Cellular Clock Theory of Aging
Cellular theories of aging propose that human aging is the result of cellular aging. The theory asserts that each cell has a pre-determined number of times that it may divide. As we age, an increasing proportion of cells reach senescence, the terminal stage at which a cell will cease to divide. The declining number of replicating cells hinders the body’s ability to regenerate or respond to injury or stress. This process will cause cell division to slow with each successive division until reaching the point where no further divisions will occur. The mechanism of replicative senescence, the point where no further cell divisions occur, is thought to involve some type of biological clock within the cell, which measures the number of cellular divisions and signals the cell to discontinue division at some genetically predetermined time. The aging process is result.
This theory proposes that aging is due to changes in neural and endocrine functions that not only selectively affect the neurons and hormones that regulate evolutionarily significant functions such as reproduction, growth, and development, but also affect those that regulate survival through adaptation to stress. Menopause is an example of an age-related hormone change, which in turn results in aging (less estrogen, greater susceptibility to conditions like osteoporosis). During the life span, chronic exposure to severe stress from a multitude of physical, biological, or emotional stimuli may exhaust or weaken the capacity to adapt and lead to the so-called “diseases of adaptation” and Aging would then result from “a decreasing ability to survive stress,” one of the many definitions of aging that suggests a close relationship between stress and longevity.
The Immunological theory of Aging
The Immunological theory of aging proposes that the immune system breaks down with aging thereby reducing the body's ability to respond effectively to foreign antigens. An impaired immune response has been linked to cancer, cardiovascular disease, inflammation, and Alzheimer's disease. This theory asserts that the aging process is the result of a jeopardized immune system.
The second groups of biological theories of aging suggest that aging is caused by damage or errors. The damage or error theories emphasize environmental assaults to living organisms that induce cumulative damage at various levels as the cause of aging. This group includes the Free Radical Theory of Aging; theCells Wear Out Theory, the Glycation Theory, and the Genome Error Theory
The Free Radical Theory of Aging
The free radical theory of aging suggests that un-partnered electrons, which are released when the body uses oxygen, cause damage to cells, DNA and entire body systems. There are molecules in the body that can absorb free radicals, and there are defense systems in the body that can repair damage. However these defensive measures are not completely effective and weaken with age. The cumulative effect of a lifetime of free radical damage and the degradation of the body's repair system becomes increasingly significant as we age.
Cells Wear Out
This theory explains our aging as the result of parts of our cells just wearing out: Each time a cell reproduces itself, the chromosome or genetic material loses a bit of the protective cap, the telomere, until the cell can no longer divide. As we age, the number of non-duplicating cells increases in proportion. At some point, system functions begin to deteriorate due to insufficient cellular replacements. This deterioration is experienced as the aging process.
The Glycation Theory
Glycation refers to the cross-linking of glucose, a sugar molecule, with a protein molecule. The result is combination molecule that binds other proteins to it and creates toxic materials. These combination molecules are called Advanced Glycation End –products, AGEs. AGEs have been linked to the toxic material found in the brains of Alzheimer’s and dementia patients, the process of thickening artery walls and of binding proteins and collagen in the skin to form wrinkles.
Genome Error Theory
The theory of Genome Error maintains that accelerated aging can be the result of damage to our DNA. Environmental toxins or spontaneous mutations can cause DNA damage. Un-repaired the damage at the cellular level can lead to cell death and organ malfunction.
What it all means...
There is not a single comprehensive explanation of the aging process. People age at different rates depending on genetics, diet, culture, activity levels and environmental exposure. An interest in the biological theories about aging is directed toward accomplishing “healthy aging”. Healthy aging from a biological standpoint combines fending off cellular and molecular damage for the longest possible time with delaying the onset of illness, disease, disability, and hence mortality for the longest possible period of time. The goals of healthy aging are best obtained by incorporating the psychosocial with the biological aspects of aging. As reported in the second edition of Handbook on Theories of Aging, research on the interconnection bio-psychosocial aspects of aging lead to some compelling conclusions.
Positive psychosocial factors predict better biological regulation than negative factors.
Positive psychosocial factors protect against the damaging effects of external adversity.
Positive psychosocial factors facilitate the regaining of functional and biological capacities.