Changing Senses

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Aging Changes in the Senses

 

Aging Changes in the Senses


Background

When you age, the way your senses (taste, smell, touch, vision, and hearing) are able to give you information about the world changes. Your senses become less acute, and you may have trouble distinguishing details. Sensory changes can have a tremendous impact on your lifestyle. You may have problems with communication, enjoyment of activities, and social interactions. Sensory changes can contribute to a sense of isolation.

All of the senses receive information of some type from the environment (light, sound vibrations, and so on). This is converted to a nerve impulse and carried to the brain, where it is interpreted into a meaningful sensation. Everyone requires a certain "minimum" amount of stimulation before a sensation is perceived (called the threshold). Aging increases this threshold, so the amount of sensory input needed to be aware of the sensation becomes greater. Changes in the body part related to the sensation (the eyes, ears, and so on) account for most of the other sensation changes.

Hearing and vision changes are the most dramatic, but all the senses can be affected by aging. Fortunately, many of the aging changes in the senses can be compensated for by with equipment (glasses, hearing aids, and so on) or by minor changes in lifestyle.

Hearing

Your ears really have two jobs. One is hearing and the other is maintaining balance. Hearing occurs after vibrations cross the eardrum to the inner ear. They are changed into nerve impulses and carried to the brain by the auditory nerve. Balance (equilibrium) is controlled in a portion of the inner ear. Fluid and small hairs in the semicircular canal (labyrinth) stimulate the nerve that helps the brain maintain balance.

With aging, ear structures deteriorate. The eardrum often thickens and the inner ear bones and other structures are affected. It often becomes increasingly difficult to maintain balance.

Hearing may decline slightly, especially high-frequency sounds. This age-related hearing loss is called presbycusis. The sharpness (acuity) of hearing may decline slightly beginning about age 50, possibly caused by changes in the auditory nerve. In addition, the brain may have a slightly decreased ability to process or "translate" sounds into meaningful information. Impacted ear wax is another common cause of trouble hearing; it is more common with increasing age.

Some hearing loss is almost inevitable. It is estimated that 30% of all people over 65 have significant hearing impairment. Conductive hearing loss occurs when sound has problems getting through the external and middle ear. Surgery or a hearing aid may be helpful for this type of hearing loss, depending on the specific cause. Sensorineural hearing loss involves damage to the inner ear, auditory nerve, or the brain. It may or may not respond to treatment. Persistent, abnormal ear noise (tinnitus) is another fairly common hearing problem, especially for older adults.

Vision

Vision occurs when light is processed by your eye and interpreted by your brain. Light passes through the transparent eye surface (cornea). Your pupil (the black opening in the front of your eye) is an opening to the eye interior. It can get larger or smaller to regulate the amount of light entering your eye. The colored portion (iris) is really a muscle controlling the pupil size. The inside of your eye is filled with a gel-like fluid. There is a flexible, transparent lens that focuses light so it hits on the back of your eye (the retina). Your retina converts light energy into a nerve impulse that is carried to the brain and then interpreted.

Some aging-related eye changes can begin as early as your 30's. Aging eyes produce less tears. Dry eyes can be quite uncomfortable. Many people find relief by using eyedrops or "artificial tears" solutions.

All of the eye structures change with aging. The cornea becomes less sensitive, so injuries may not be noticed. The pupil size decreases by 60 years old to 1/3 of the size it was at age 20. The pupil may also change size slower in response to darkness or bright light. The lens becomes yellowed, less flexible, and slightly cloudy. The fat pads supporting the eye decrease and the eye "sinks" back into the socket. The eye muscles become less able to fully rotate the eye.

As you age, the sharpness of your vision (visual acuity) may gradually decline. Glasses or contact lenses may help correct age-related vision changes. Bifocals may eventually be needed. Almost everyone older than 55 needs glasses at least part of the time. However, the amount of change is not universal. Only 15 - 20% of older people have bad enough vision to impair driving ability, and only 5% become unable to read. The most common problem is difficulty focusing the eyes (a condition called presbyopia).

You may be less able to tolerate glare, and find that you have more trouble adapting to darkness or bright light. Many older people find that, while their vision is good enough to drive during the day, they must give up night driving because of these 2 problems. Glare from shiny floors in a sunlit room can also make it difficult to get around inside.

For people of all ages, it is harder to tell blues and greens from each other than it is to tell apart reds and yellows. This becomes even more pronounced with aging. As your age increases, using lots of warm contrasting colors (yellow, orange, and red) in your home can improve your ability to tell where things are and makes it easier to perform daily activities. Many older people find that keeping a red light on in darkened rooms (such as the hallway or bathroom) makes it easier to see than keeping a "regular night light" on.

With aging, the fluid inside your eye may change. Small particles can create "floaters" in your vision. Although annoying, these "floaters" do not indicate a dangerous condition and usually do not reduce vision.

When your eyes are examined, you may not be able to move your eye in all directions. The upward gaze may be limited. The area in which objects can be seen (visual field) gets smaller. Reduced peripheral vision is common, and can limit social interaction and activity. Older people may not communicate with people sitting next to them because they cannot see them. Food and drinks may be spilled. Driving can become dangerous.

Common eye disorders in the elderly (changes that are NOT normal) include cataracts, glaucoma, senile macular degeneration, and diabetic retinopathy.

Taste and Smell

The senses of taste and smell interact closely to help you appreciate food. You have approximately 9,000 taste buds. Your taste buds are primarily responsible for sensing sweet, salty, sour, and bitter tastes.

Most "taste" really comes from odors. The sense of smell begins at nerve receptors high in the membranes of the nose.

Smell (and to a lesser extent, taste) also play a role in both our safety and enjoyment. We detect certain dangers, such as spoiled food, noxious gases, smoke, and so on with taste and smell. A delicious meal or pleasant aroma can improve social interaction and enjoyment of life.

Aging changes in taste and smell are not definitely shown. There is evidence that normal aging diminishes both these sensations.

The number of taste buds decreases beginning at about 40 to 50 years old in women and 50 to 60 years old in men. Each remaining taste bud also begins to lose mass (atrophy). The sensitivity to the 4 taste sensations does not seem to decrease until after age 60 if at all. If taste sensation is lost, usually salty and sweet tastes are lost first, with bitter and sour tastes lasting slightly longer.

Additionally, with aging the mouth produces less saliva. This causes dry mouth, which can make swallowing more difficult. It also makes digestion slightly less efficient.

The sense of smell may diminish, especially after age 70. This may be related to loss of nerve endings in the nose.

Studies about the cause of decreased sense of taste and smell with aging have conflicting results. Some studies have indicated that normal aging by itself produces very little change in taste and smell. Rather, changes may be related to diseases, smoking, and other environmental exposures over a lifetime.

Regardless of the cause, decreased taste and smell can lessen your interest and enjoyment in eating. Some people become less aware of personal hygiene when the sense of smell is decreased. Enjoyment of your environment may be less. Sometimes, changes in the way food is prepared, such as a change in the spices used, can help.

For some people, there is an increased risk of asphyxia because they cannot detect the odor of natural gas (from the stove, furnace, or other appliance). A visual "gas detector" that changes appearance when natural gas is present may be helpful.

Touch, Vibration and Pain

The sense of touch also includes awareness of vibrations and pain. The skin, muscles, tendons, joints, and internal organs have receptors that detect touch, temperature, or pain.

Your brain interprets the type and amount of touch sensation. It also interprets the sensation as pleasant (for example, comfortable warmth), unpleasant (for example, very hot), or neutral (such as awareness that you are touching a surface). Medications, brain surgery, problems in the brain, confusion, and other things can change this interpretation without changing awareness of the sensation. For example, the person may feel and recognize a painful sensation, but it does not bother them.

Some of the receptors give the brain information about the position and condition of internal organs. Even though you may not be consciously aware of this information, it helps to identify changes (for example, the pain of appendicitis).

Many studies have shown that, with aging, you may have reduced or changed sensations of pain, vibration, cold, heat, pressure, and touch. It is hard to tell if these changes are related to aging itself, or to the disorders that occur more often in the elderly. It may be that some of the "normal" changes of aging are caused by decreased blood flow to the "touch" receptors, or to the brain and spinal cord. Minor dietary deficiencies, such as decreased thiamin levels, may also be a cause of changes.

Regardless of the cause, many people experience changes in the touch-related sensations as they age.

You may find it harder, for example, to tell the difference between cool and cold. Decreased temperature sensitivity increases the risk of injuries such as frostbite, hypothermia, and burns.

Reduced ability to detect vibration, touch, and pressure increases the risk of injuries, including pressure ulcers. After age 50, many people have reduced sensitivity to pain. You may develop problems with walking because of reduced ability to perceive "where the body is" in relation to the floor.

Fine touch may decrease. However, some people develop an increased sensitivity to light touch because of thinner skin (especially people older than 70 years old).

To increase safety, make allowances for changes in touch-related sensations. For example, limit the maximum water temperature in your house (there is an adjustment on the water heater) to reduce the risk of burns. Look at the thermometer to decide how to dress rather than waiting until you feel overheated or chilled. Inspect your skin for injuries, and if you find an injury, treat it. Don't assume that just because an area is not painful, the injury is not significant.

Related Topics:

aging changes in organs, skin, tissues, and cells http://www.healthcentral.com/mhc/top/004012.cfm

aging changes in the bones, muscles, and joints http://www.healthcentral.com/mhc/top/004015.cfm

aging changes in the face http://www.healthcentral.com/mhc/top/004004.cfm

aging changes in the nervous system http://www.healthcentral.com/mhc/top/004023.cfm

http://www.healthcentral.com/mhc/top/004013.cfm?

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