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 loss. They can support them with resolving any issues resulting from the visual impairments. Counselors can also encourage or make referrals for optical devices (e.g., eye glasses, larger numbers on their phones). Counselors can provide strategies to live independently with redesigning their environment, and they can also monitor their compliance with any treatment regimes. Loss of independence will be a concern for many older adults who are visually impaired, and counselors are positioned to facilitate the relocation to another environment (if necessary) and to offer resources as alternatives for loss of ability to drive. Counselors will provide support, encouragement, coping strategies, referrals, and resources to make the transition easier for older adults, while maintaining a focus on strengths and capabilities versus disabilities with older clients.
Vision is affected in various ways due to aging. Changes occur in the components of the eye itself and in central processing in the brain. These changes affect reading, balance, and driving, but compensatory glasses and behavior can maintain safety. As the eyes age, it is normal for older adults to have a reduced visual field. Pure aging makes clear that no disease, environmental, lifestyle, or behavioral risk factor plays a role in the change. It includes a decline in accommodation, which is the increase in optical power by the eye in order to maintain a clear image (focus) as objects are moved closer (e.g., presbyopia or farsightedness). Low-contrast acuity refers to the sharpness or keenness of vision. Glare tolerance declines, as does adaptation (adjustment to environmental conditions) and color discrimination. Also, there is a decreased attentional visual field that describes a person’s ability to divide attention and extract visual information from the visual field within a glance. The common eye diseases in old age (e.g., glaucoma, macular degeneration, cataracts, diabetic retinopathy) are superimposed upon these pure aging changes (Besdine & Wu, 2008).
Older individuals may begin to have difficulties with contrast sensitivity, in which the difference between an object and its background is reduced. This reduction in sensitivity is gradual because of progressive eye problems that can lead to scarring or clouding of the cornea, which decreases vision. Decreased contrast sensitivity also diminishes an elderly person’s ability to perceive depth. Reduced depth perception makes steps or street curves difficult to manage. Additionally, seeing at night can become difficult. A person with early nuclear sclerosis (cloudiness of the eye lens) may complain of glare especially during night driving, due to light scattering, which is light directed in many different directions. At the same time, older people need more lighting in their surroundings than a younger person. Beginning in the early mid-40s, most adults start to experience problems with their ability to see clearly at close distances, especially for reading and computer tasks.
A reduction in number of cones at the fovea causes generalized reduction in color vision. Fovea is the central focal point on the retina (lines the back of the eye) around which cones cluster. Cones are photoreceptors located near the center of the retina that are responsible for your ability to see during the day, in color, and in detail. For people of all ages, it is harder to distinguish blues and greens than it is to differentiate reds and yellows. This becomes even more pronounced with age. Using more warm contrasting colors (e.g., yellow, orange, and red) in the home can improve the ability to determine where things are and make it easier to perform activities of daily living. Many older people find that