“Senses” are commonly defined as the physiological capacities within organisms that provide inputs for perception of the environment. There are varying opinions about what perceptive capabilities constitute a “sense,” but there are five basic senses that provide the vast majority of critical stimuli humans rely on for everyday living. These are sight, hearing, touch, smell and taste. Each of these five senses provides very distinct sets of stimuli to our brains, but we process them together to develop complete perceptions of our world. As we grow up, and ultimately grow older, however, each of these five senses changes slowly, often imperceptibly, but nonetheless consistently.
We have all heard the phrase “The first thing to go is your…” The fact is, it’s different for everyone, depending on your life experience (injuries, maladies, persistent environmental conditions, etc.) and genetic predispositions. Each of us will have to deal with changes in sensory capabilities, and the impact these changes have on their lives, in our own distinct way. This article outlines what each of the senses are, how and why they are likely to change over time, and the impact these changes have on our lives.
Hearing affects our ability to appreciate life, such as a favorite song. Once hearing is impaired, there may also be balance issues that ensue. Over one-third of those over 65, and half of those over 85 have some hearing loss. Age-related hearing loss is called presbycusis, and can lead to social isolation and depression, as well as cause falls because hearing contributes to balance.
Unfortunately, hearing loss is often under diagnosed and under-treated. This may be because assessment of hearing and hearing aids has not been covered under Medicare or most other health plans. Another potential reason for under diagnosis is that hearing loss often occurs gradually, leaving us unaware of subtle changes. Signs to look for are frustration when talking to family members, problems
tell our brain how to interpret the touch. As we age, the nerve fibers lose the ability to transmit messages to the brain. The end result is that after touching a hot object, the brain does not interpret the object as hot, and we therefore do not withdrawal immediately from touching the object. The same type of phenomenon occurs in diabetics due to nerve damage from high blood sugars. The loss or impairment of the ability to feel anything touched is called tactile anesthesia.
There are approximately 9,000 taste buds on the human tongue. They tell us if a substance is sweet, sour, bitter or salty. Over time, the number of taste buds decreases, usually starting between the ages of 40 and 50 in women and 50 to 60 in men. In addition, the remaining taste buds may actually become smaller, a process called atrophy. This means that enjoyment of foods may diminish over time. Some researchers believe this is why older people often enjoy foods with strong tastes. It is usually salty and sweet taste buds that are lost first. A complete inability to taste is called ageusia.
Smell, like hearing, is a sense that acts on the emotion and memory centers of the brain. When we smell we are actually smelling with our brain. Molecules from the air enter the nose and attach to nerve endings that send signals to the brain. The signals tell the brain if the smell is good or bad and then our brain attaches the smell to either a good or bad mood or memory.
As with taste, once smell is diminished there may be less enjoyment for the elderly to engage in eating. It can also lead to decreased attention to hygiene, and to potential dangers in the home. For instance, spoiled food, a gas leak, or smoke may not be detected by a person with decreased smell. A complete inability to smell is called anosmia.
understanding conversations in noisy rooms, and difficulty watching television. With presbycusis, consonants are a problem in conversation, making the subtle sounds made by the letters z, s, f, p, g, or t difficult to understand. Ironically, raising your voice makes consonant harder to hear, so speaking louder can actually make it harder for those with hearing loss to understand you.
While hearing loss from presbycusis is helped by hearing aids, some loss is caused by reduced ability to conduct sound through the ear. For example, impacted ear wax is common in the elderly due to increased water loss. The inability to hear is called deafness.
Vision loss can occur at any time, but as we age there are changes that occur with muscles around the eyes and our pupils that result in a decreased ability to adjust to changes in distance and light. Weakness in the muscles that support the eye and help with movement can cause headaches when older people have to look at close objects for a long period of time. As we age, the pupils get smaller, allowing less light to reach the retina in the back of the eye. The lens also becomes cloudy and lose curvature, leaving it unable to refract light as well. You may notice this first while driving at night when the lens needs to curve more in order to discern objects.
As with other physical changes, it is important to recognize when a change in the eyes is not due to a normal function of aging, but instead to an abnormal occurrence. Continuing with the example of vision changes at night, this may also be a sign of developing cataracts or macular degeneration. A complete inability to see is called blindness.
Touch incorporates not only texture and temperature, but also vibration and pain. It helps warn us of danger. Sense of touch occurs from nerve fibers on the skin that send signals