The Nervous System and Aging

The Nervous System and Aging

Sensory changes can influence the way we see, hear, taste, smell, and respond to touch and pain. This in turn affects how we experience the world and react to things. A significant sensory change can rob us of many simple pleasures and complicate the tasks of daily living. It may mean reduced mobility, increased dependence on others, inaccurate perception of the environment, reduced ability to communicate and socialize, or loss of self-esteem.

Sensory changes vary from person to person. Fortunately, until their mid 80s most older adults are free of major sensory problems.

The senses become less efficient with age. But age is not the only factor causing deterioration in the senses. Disease and environmental factors are also important. Intense and prolonged noise affects hearing, smoking reduces taste and smell sensitivity, and diabetes may affect vision.

Changes in vision and hearing are particularly important because they can affect the person's ability to function in the physical environment and may lead to isolation.

Vision:

Common Age-Related Changes

Several aspects of vision change with age. Normal age-related changes in vision include:

Decrease in sharpness of vision (visual acuity)
Decrease in the ability to focus on objects at different distances
Decrease in ability to discriminate between certain colors
Decrease in ability to function in low light levels and adapt to dark
Decrease in ability to adapt to glare
Decrease in ability to judge distances
Most older people have fairly good vision into their 70s and 80s. However, an estimated 10 percent of people age 65 to 75 have impaired vision to such a degree that it affects their ability to function; 16 percent of people age 75 to 84 and 27 percent of those 85 years and older have this level of impairment.

Persons with vision loss may experience problems with mobility, poor orientation, and frightening visual impressions that resemble hallucinations. They often feel more vulnerable to danger and crime. Otherwise fastidious people may wear soiled clothing because they can't see stains and food spills. They may reduce or eliminate such pastimes as reading or watching television.

According to the National Center for Health Statistics, vision impairment is strongly associated with greater difficulty in performing daily activities such as walking, getting outside, and transferring in and out of a bed or chair. Poor vision also increases the likelihood of falling.

Hearing
A hearing loss is potentially the most serious of the sensory impairments because it is our "social sense." Unlike poor vision, hearing loss rarely inspires empathy and understanding. The seeing-eye dog, thick glasses, and white cane all help identify the blind and visually impaired, but the person who is hard of hearing is not as easily identified. In regard to her deafness, Helen Keller, who was both deaf and blind, stated:

"I am just as deaf as I am blind. The problems of deafness are deeper and more complex, if not more important than those of blindness. Deafness is a much worse misfortune. For it means the loss of the most vital stimulus--the sound of the voice that brings language, sets thoughts astir, and keeps us in the intellectual company of man."

Hearing loss affects more older people than any other chronic condition. From age 20 to 60, the rate of hearing impairments increases from 10 to 75 per 1,000 people. Between the ages of 60 and 80, the rate increases to 250 per 1,000 people. Approximately 30 to 50 percent of all older people suffer a significant hearing loss that affects their communication and relationships with others.

Hearing loss can be devastating. It can lead to withdrawal, isolation, and depression. Even a slight loss can be emotionally upsetting, particularly if it interferes with understanding family and friends. Trying to understand conversation becomes frustrating and exhausting. Many people will withdraw from group situations, restrict their activities, and stay at home when it becomes difficult to listen and understand the conversation around them.

Misunderstood conversations can lead to suspiciousness, paranoia, disagreements, and alienation from family and friends. Older people who try to cope by responding to what they think is said may be viewed as cognitively impaired, rather than hearing impaired.

"Silence is golden. But the silence that comes from a hearing loss can make for loneliness." --84-year-old man

Travel by public transportation can be difficult, particularly if announcements over intercoms are unclear. Sounds that shape our daily lives--doorbells, telephones, alarm clocks--may not be heard. A person with impaired hearing is at high risk if he or she doesn't hear warning signals such as fire alarms and horns. A hearing loss may complicate adjustment to other age-related losses.

Taste and Smell For people to maintain good nutrition, food must be appealing to their sense of taste and smell. However, with increasing age, decline in these senses can affect the pleasure and satisfaction older people obtain from food.

The number and sensitivity of the taste buds decrease with age. After the age of 50, the ability to perceive each of the taste sensations--sweet, salty, bitter, and sour--declines, but not at the same rate. The decline appears greatest for salt sensitivity.

The sense of taste appears not to decline significantly as much from aging as from other factors--smoking, poor oral hygiene, dentures that rub on the tongue, and certain medical conditions. Diabetics are less able to detect certain flavors. Cancer changes or intensifies certain taste perceptions, causing abnormal taste sensation. Some medications decrease taste perception; others accentuate it.

Saliva, which is necessary for taste, decreases in later life. The taste of "sour" tends to stimulate saliva flow. This can be demonstrated by popping a lemon drop candy into your mouth. Some medications and radiation treatments to the head and neck also can decrease saliva.

Older people who experience changes in their ability to taste may complain "Food just doesn't taste as good as it did when I was younger," or "Everything tastes flat." When food no longer tastes good, people can lose their interest in eating, which sometimes leads to malnutrition. Others will overeat in an attempt to achieve a favorable taste sensation. They may begin to use more salt, sugar, or spices to compensate for lack of taste.

Older people who have poor vision and have lost their taste sensitivity often find it difficult to identify foods. Food may have little appeal to them. Diet restrictions (bland or low-salt diets) can contribute further to food being unappealing. Poor health, low physical energy, not wanting to prepare a meal for just one person, and limited budgets also cause some older people to eat poorly.

Aging appears to affect the sense of smell more than the sense of taste. The sense of smell may be the earliest sensory system to decline, beginning as early as the late 30s or early 40s. After age 80, there is major impairment in the sense of smell. One major study showed that 60 percent of people in their 60s and 70s showed impairment and 25 percent could not identify odors. Eighty percent of the subjects over age 80 showed impairment; 50 percent had complete loss of the sense of smell. The exact mechanism for this decline is not known.

Changes in the ability to smell have important consequences for nutrition, safety, personal hygiene, and enjoyment of life. Without the sense of smell the world changes. The aroma of favorite foods lose their ability to entice. The aroma of an apple pie baking, the smell of coffee brewing, the fragrance of spring flowers, or the scent of the Christmas tree are gone.

Loss of the ability to smell also affects safety. It is less likely the person will be able to detect warning odors--gas leak, smoke, or spoiled food. Smoke alarms and pilot lights can decrease the potential hazards that loss of smell creates, especially for older persons living alone. The person may not be able to detect personal body or household odors, or pet wastes that are offensive to others. Perfume and cologne may be heavily applied and overpowering to other people.

Touch The sense of touch enables us to distinguish between objects, enjoy the touch of another person, and be aware of danger, for example from hot or sharp objects. Many of our daily activities rely on the sense of touch.

Touch sensitivity and the ability to detect pain decreases with age. Certain chronic diseases such as diabetes, circulation problems, stroke, Parkinson's disease, and arthritis can further affect a person's sense of touch.

Some older persons find it difficult to distinguish textures and objects on the basis of touch alone. Some may experience a delayed reaction to being touched.

Pain threshold increases with age. Certain medical problems and medications may further reduce sensitivity to pain. An older adult is more likely to suffer a severe burn or cut before noticing discomfort. He or she may not feel the hot temperature of bath water or a heating pad.

Compared to a younger person, an older person also is less likely to perceive internal body pain or a rising temperature. This may result in an illness or infection progressing to an advanceD stage before detection. This is particularly common and potentially dangerous in the older person who has diabetes. Because diabetes contributes to loss of nerve sensitivity and blood flow in the feet and legs, severe cuts and bruises may not be noticed, and severe infection may result.

Precautions such as lowering the temperature setting of a hot water heater can reduce the likelihood of accidents due to decreased touch and pain sensitivity. Lowering the temperature to 120°F is recommended.

The use of touch can be a powerful therapeutic tool. Yet, some older adults are touched very little or not at all and suffer from "touch hunger." Touch is a powerful means of communication. It can help reduce anxiety and provide comfort. When using touch, consider the person's background, culture, and sense of personal space