Vision

In late adulthood, all the senses show signs of decline, especially among the oldest-old. In the last chapter, you read about the visual changes that were beginning in middle adulthood, such as presbyopia, dry eyes, and problems seeing in dimmer light. By later adulthood these changes are much more common. Three serious eyes diseases are also more common in older adults: cataracts, macular degeneration, and glaucoma. Only the first can be effectively cured in most people.

Cataracts

Cataracts are a clouding of the lens of the eye. The lens of the eye is made up of mostly water and protein. The protein is precisely arranged to keep the lens clear, but with age some of the protein starts to clump. As more of the protein clumps together the clarity of the lens is reduced. While some adults in middle adulthood may show signs of cloudiness in the lens, the area affected is usually small enough not to interfere with vision. More people have problems with cataracts after age 60 (NIH, 2014) and by age 75, 70% of adults will have problems with cataracts (Boyd, 2014). Cataracts also cause a discoloration of the lens, tinting it more yellow and then brown, which can interfere with the ability to distinguish colors such as black, brown, dark blue, or dark purple.

Risk factors besides age include certain health problems such as diabetes, high blood pressure, and obesity, behavioral factors such as smoking, other environmental factors such as prolonged exposure to ultraviolet sunlight, previous trauma to the eye, long-term use of steroid medication, and a family history of cataracts (NEI, 2016a; Boyd, 2014). Cataracts are treated by removing and replacing the lens of the eye with a synthetic lens. In developed countries, such as the United States, cataracts can be easily treated with surgery.

However, in developing countries, access to such operations are limited, making cataracts the leading cause of blindness in late adulthood in the least developed countries (Resnikoff et al., 2004). As shown in Figure 8.4, in areas of the world with limited medical treatment for cataracts, people are living more years with a serious disability. For example, of those living in the darkest red color on the map, more than 990 out of 100,00 people have a shortened lifespan due to the disability caused by cataracts.

Macular degeneration

Older adults are also more likely to develop age-related macular degeneration, which is the loss of clarity in the center field of vision, due to the deterioration of the macula, the center of the retina. Macular degeneration does not usually cause total vision loss, but the loss of the central field of vision can greatly impair day-to-day functioning. There are two types of macular degeneration: dry and wet. The dry type is the most common form and occurs when tiny pieces of a fatty protein called drusen form beneath the retina. Eventually the macular becomes thinner and stops working properly (Boyd, 2016). About 10% of people with macular degeneration have the wet type, which causes more damage to their central field of vision than the dry form. This form is caused by an abnormal development of blood vessels beneath the retina. These vessels may leak fluid or blood causing more rapid loss of vision than the dry form.

The risk factors for macular degeneration include smoking, which doubles your risk (NIH, 2015); race, as it is more common among Caucasians than African Americans or Hispanics/Latinos; high cholesterol; and a family history of macular degeneration (Boyd, 2016). At least 20 different genes have been related to this eye disease, but there is no simple genetic test to determine your risk, despite claims by some genetic testing companies (NIH, 2015). At present, there is no effective treatment for the dry type of macular degeneration. Some research suggests that some patients may benefit from a cocktail of certain antioxidant vitamins and minerals, but results are mixed at best. They are not a cure for the disease nor will they restore the vision that has been lost. This “cocktail” can slow the progression of visual loss in some people (Boyd, 2016; NIH, 2015). For the wet type, medications that slow the growth of abnormal blood vessels and surgery, such as laser treatment to destroy the abnormal blood vessels, may be used. Unfortunately, only 25% of those with the wet version typically see improvement with these procedures (Boyd, 2016).

Glaucoma

A third vision problem that increases with age is glaucoma, which is the loss of peripheral vision, frequently due to a buildup of fluid in eye that damages the optic nerve. As we age the pressure in the eye may increase causing damage to the optic nerve. The exterior of the optic nerve receives input from retinal cells on the periphery, and as glaucoma progresses more and more of the peripheral visual field deteriorates toward the central field of vision. In the advanced stages of glaucoma, a person can lose their sight entirely. Fortunately, glaucoma tends to progresses slowly (NEI, 2016b).

Glaucoma is the most common cause of blindness in the U.S. (NEI, 2016b). African Americans over age 40, and everyone else over age 60, have a higher risk for glaucoma. Those with diabetes, and with a family history of glaucoma also have a higher risk (Owsley et al., 2015). There is no cure for glaucoma, but its rate of progression can be slowed, especially with early diagnosis. Routine eye exams to measure eye pressure and examination of the optic nerve can detect both the risk and presence of glaucoma (NEI, 2016b). Those with elevated eye pressure are given medicated eye drops. Reducing eye pressure lowers the risk of developing glaucoma or slow its progression in those who already have it.

Hearing

As you read previously, our hearing declines both in terms of the frequencies of sound we can detect, and the intensity of sound needed to hear as we age. These changes continue in late adulthood. Almost 1 in 4 adults aged 65 to 74 and 1 in 2 aged 75 and older have disabling hearing loss (NIH, 2016). Table 8.1 lists some common signs of hearing loss.

Table 8.1 Common Signs of Hearing Loss

adapted from NIA, 2015

Presbycusis is a common form of hearing loss in late adulthood that results in a gradual loss of hearing. It runs in families and affects hearing in both ears (NIA, 2015b). Older adults may also notice tinnitus, a ringing, hissing, or roaring sound in the ears. The exact cause of tinnitus is unknown, although it can be related to hypertension and allergies. It may come and go or persist and get worse over time (NIA, 2015b). The incidence of both presbycusis and tinnitus increase with age and males around the world have higher rates of both (McCormak et al., 2016).

Your auditory system has two jobs: To help you to hear, and to help you maintain balance. Your balance is controlled when the brain receives information from the shifting of hair cells in the inner ear about the position and orientation of the body. With age, the functionality of the inner ear declines, which can lead to problems with balance when sitting, standing, or moving (Martin, 2014).

Taste and Smell

Our sense of taste and smell are part of our chemical sensing system. Our sense of taste, or gustation, appears to age well. Normal taste occurs when molecules that are released by chewing food stimulate taste buds along the tongue, the roof of the mouth, and in the lining of the throat. These cells send messages to the brain, where specific tastes are identified. After age 50, we start to lose some of these sensory cells. Most people do not notice any changes in taste until their 60s (NIH: Senior Health, 2016). Given that the loss of taste buds is very gradual, even in late adulthood, many people are often surprised that their loss of taste is most likely the result of a loss of smell.

Our sense of smell, or olfaction, decreases with age, and problems with the sense of smell are more common in men than in women. Almost 1 in 4 males in their 60s have a disorder with the sense of smell, compared to 1 in 10 women (NIH: Senior Health, 2016). This loss of smell due to aging is called presbyosmia. Olfactory cells are located in a small area high in the nasal cavity. These cells are stimulated via two pathways: when we inhale through the nose, or via the connection between the nose and the throat when we chew and digest food. It is a problem with this second pathway that explains why some foods such as chocolate or coffee seem tasteless when we have a head cold. There are several types of loss of smell. Total loss of smell, or anosmia, is extremely rare.

Problems with our chemical senses can be linked to other serious medical conditions such as Parkinson’s, Alzheimer’s, or multiple sclerosis (NIH: Senior Health, 2016). Any sudden changes in sensory sensitivity should be checked out. Loss of smell can change a person’s diet, with either a loss of enjoyment of food and eating too little for balanced nutrition, or adding sugar and salt to foods that are becoming blander to the palette.

Table 8.2 Problems with Smell

Table 7.2 Types of Smell Disorders

adapted from NIH Senior Health: Problems with Smell

Touch

Research has found that with age, people may experience reduced or changed sensations of vibration, cold, heat, pressure, and pain (Martin, 2014). Many of these changes are also consistent with a number of medical conditions that are more common among the elderly, such as diabetes. However, there are also changes in touch sensations among healthy older adults. The ability to detect changes in pressure have been shown to decline with age, with more pronounced losses during the 6th decade and diminishing further with advanced age (Bowden & McNelty, 2013). Yet, there is considerable variability, with almost 40% of the elderly showing sensitivity that is comparable to younger adults (Thornbury & Mistretta, 1981). However, the ability to detect the roughness/ smoothness or hardness/softness of an object shows no appreciable change with age (Bowden & McNulty, 2013). Those who show decreasing sensitivity to pressure, temperature, or pain are at risk for injury (Martin, 2014), as they can injure themselves without detecting it.

Pain

According to Molton and Terrill (2014), approximately 60%-75% of people over the age of 65 report at least some chronic pain, and this rate is even higher for those individuals living in nursing homes. Although the presence of pain increases with age, older adults are less sensitive to pain than younger adults (Harkins et al., 1986). Farrell (2012) looked at research studies that included neuroimaging techniques involving older people who were healthy and those who experienced a painful disorder. Results indicated that there were age-related decreases in brain volume in those structures involved in pain. Especially noteworthy were changes in the prefrontal cortex, brainstem, and hippocampus.

Women are more likely to report feeling pain than men (Tsang et al., 2008). Women have fewer opioid receptors in the brain, and women also receive less relief from opiate drugs (Garrett, 2015). Because pain serves an important indicator that there is something wrong, a decreased sensitivity to pain in older adults is a concern because it can conceal illnesses or injuries requiring medical attention.

Chronic health problems, including arthritis, cancer, diabetes, joint pain, sciatica, and shingles are responsible for most of the pain felt by older adults (Molton & Terrill, 2014). Cancer is a special concern, especially “breakthrough pain” which is a severe pain that comes on quickly while a patient is already medicated with a long-acting painkiller. It can be very upsetting, and after one attack many people worry it will happen again. Some older individuals worry about developing an addiction to pain medication, but if medicine is taken exactly as prescribed, addiction should not be a concern (NIH, 2015a). Lastly, side effects from pain medicine, including constipation, dry mouth, and drowsiness, may occur that can adversely affect the elder’s life.

Some older individuals put off going to the doctor because they think pain is just part of aging and nothing can help. Of course, this is not usually true. Managing pain is crucial to ensure feelings of well-being for the older adult. When chronic pain is not managed, the individual tends to restrict their movements for fear of feeling pain or injuring themselves further. This lack of activity will result in more restriction, further decreased participation, and greater disability (Jensen et al., 2011). A decline in physical activity because of pain is also associated with weight gain and obesity in adults (Strine et al., 2005). Additionally, sleep and mood disorders, such as depression, can occur (Moton & Terrill, 2014). Learning to cope effectively with pain is an important consideration in late adulthood and working with one’s primary physician or a pain specialist is recommended (NIH, 2015a).

Of those 65 and older, 35% have a disability. Figure 8.10 identifies the percentage of those who have a disability based on the type.