to the gradual accumulation of mutated cells that do not perform normally. Genetic mutations occur and accumulate with increasing age, causing cells to deteriorate and malfunction (Jin, 2010). This leads to cellular dysfunction such as cancer. Different organs may develop diseases and some may be spared; however, these mutations are uncontrolled.
Wear and Tear Theory of Aging
The wear and tear theory of aging is an early theory that proposes that the body wears out (Cristofalo, 1988). This theory is difficult to test, as normal wear and tear has not been defined, and the breakdown of various body systems cannot be predicted (Hayflick, 1996). The wear and tear theory postulates that the daily grind of life, in particular abuse or overuse, literally wears the body out, leading to disease states. This theory proposes that vital parts of our cells and tissues wear out resulting in aging (Jin, 2010). Wear and tear is an accumulation of errors and damage due to natural use (MacWilliam, 2002). The degeneration of cartilage and eventual grinding of bone on bone is an example of the aging process on body joints, as wear and tear exceeds the body’s ability to repair. This theory was the first theory that attempted to explain aging as a result of damage accumulated over time and laid the foundation for other scientists to explore additional explanation as to why and how the body ages.
Table 1.1
Though none of these major biological theories encapsulate the aging process on its own, they are each an important piece of the aging puzzle. Table 1.1 provides a brief overview of the theories and what they contribute to the knowledge of aging.
The various theories identified are an attempt to explain why the body ages from the biological perspective and causes the physical changes that older persons experience.
Physical Changes That Accompany Aging
Adulthood is a time of life characterized mostly by personal growth and stability, but over the adult life span, loss and decline begins (Heckhausen, 2001). Age-related declines in physical function are observed from midlife onward, even in the absence of disease, as a result of normal age-related changes in the musculoskeletal system and other body systems (Cooper, Kuh, & Cooper, 2011). It is important to remember that no two people age at the same rate. Levels of stability or decline differ greatly in areas of physical, sensory, and cognitive functioning.
Physically, some of the most noticeable signs of aging include the loss of pigmentation leading to the graying of hair, thinning of hair caused by hair germination center destruction, rigidity of the skin’s dermal layer leading to wrinkling, and changes in the strength and tone of voice (Whitbourne, 2001). Less noticeable signs of aging, which may affect most individuals in adulthood, include a decrease in bone density, decline in muscle mass, visual and auditory deterioration, changes in cardiovascular fitness and respiratory functioning, and changes in body regulation (e.g., decreased basal metabolism rates, endocrine and immune function, and sexual changes) (Masoro & Austad, 2001).
Typically, older people walk more slowly, have less muscle strength, have poorer memory and reasoning abilities, and are slower to respond on cognitive tasks relative to younger adults and to themselves when they were younger. Physical and cognitive functioning are both indicators of biologic aging. The aging process is often characterized by a loss of adaptive response to life challenges and an increasing vulnerability to pathology (i.e., aging-associated diseases) and functional limitations. However, biological aging is not tied absolutely to chronological aging. It may be possible to slow biological aging and even reduce the possibility of suffering from age-related diseases such as dementia (Peters, 2006). Many natural changes occur in the aging process, and the central nervous system is the major mechanism behind all changes.
Central Nervous System
The nervous system is the body’s control center. It controls the body’s movements, senses, thoughts, and memories. It also controls the organs such as the heart and bowels. There are two parts to the nervous system: the central nervous system, which is made up of the brain and spinal cord, and the peripheral nervous system, which is mainly comprised of nerves. The spinal cord is the bundle of nerves that runs from the brain down the center of the back. Nerves extend out from the spinal cord to every part of the body (Dugdale, 2012) and are the pathways that carry signals between the brain and the rest of the body.
As the body ages, the central and peripheral nervous systems go through natural changes. The brain and spinal cord lose nerve cells and weight (atrophy). Nerve cells may begin to pass messages more slowly. Waste products can collect in the brain tissue as nerve cells break down, causing abnormal changes in the brain called plaques and tangles to form. A fatty brown pigment (lipofuscin) can also build up in nerve tissue, which can impair the functioning of seemingly unrelated cellular systems. Lipofuscin has also been associated with dementia and severe memory loss. Breakdown of nerves affect the senses, causing reduced or lost reflexes or sensation, which can lead to problems with movement and safety.
The slowing of thought, memory, and thinking is a normal part of aging. This is caused by changes to the brain’s size, blood vessels, and cognition. As it ages, the brain shrinks in volume, particularly in the frontal cortex. As we age, the blood vessels may stiffen and blood pressure rises, and may result in inadequate oxygen to the heart muscle (ischemia), and a narrowing or blockage of one or more arteries may lead to a stroke and subsequent lesion (area of tissue that has been damaged through injury or disease). As a person’s vasculature ages and blood pressure rises, the possibility of stroke and ischemia increases, and the brain’s white matter develops lesions. Memory decline also occurs, and brain activation becomes more bilateral (use of left and right prefrontal cortex) for memory tasks because older brains tend to show more symmetrical activation (using both the left and right hemispheres). This may be an attempt to compensate and use additional networks or because specific areas are no longer easily accessed. These anatomical changes are linked to a number of functional alterations. In general, neural processing becomes less efficient. For example, memory consolidation often becomes more difficult, and sensory systems of the elderly, notably hearing, balance, vision, smell and taste, become less acute. Light must be brighter, sounds louder, and smells stronger before they are perceived (American Academy of Health and Fitness [AAHF], 2015). Genetics, neurotransmitters, hormones, and experience all play a role in how quickly the brain ages.
Sensory Perception
Some sensory changes begin in early middle age. They are progressive and are apt to cause limitation of activity in later years. All sensory organs show some degree of altered function by the age of 70. In general, the changes in sensory function due to aging include a higher sensory threshold (level of strength a stimulus must reach to be detected) and a decrease in sensory acuity (actual physical ability of the sensory organs to receive input). Natural changes in vision, hearing, taste, and smell occur as one ages.
Vision
A reduction in vision can have a negative psychological impact on many aspects of functioning in older adults. Older adults may not be able to enjoy leisure activities such as reading, watching television, playing chess/checkers, finishing crossword puzzles, and a host of other activities. A loss of vision may impede social activities and physical activities, which will eventually negatively impact their emotional and physical health. Loss of vision will impact their ability to remain independent in their homes and also negatively impact their ability to drive. Older adults may suffer unnecessary falls due to their decreased vision. Self-esteem will be adversely affected, interaction with significant others will be challenging and their overall quality of life is diminished. Counselors can help older adults adjust to their vision
