Making Sense of the Senses... Part Two
All of the eye structures change with aging. By the time you turn 60, your pupils may decrease to about one third of the size they were when you were 20. The pupils may react more slowly in response to darkness or bright light. The lens becomes yellowed, less flexible, and slightly cloudy.
The sharpness of your vision gradually declines with difficulty focusing on close-up objects. Glare is tolerated less and you have trouble adapting to darkness or bright light. Older people have reduced peripheral vision and experience difficulties differentiating colours – particularly blues.
Your sense of smell can diminish, especially after age 70. This may be related to a loss of nerve endings and less mucus production in the nose. Mucus helps odours stay in the nose long enough to be detected by the nerve endings. It also helps clear odours from the nerve endings.
The number of taste buds decreases as you age. Each remaining taste bud also begins to shrink. Sensitivity to the five tastes often declines after age 60. In addition, your mouth produces less saliva as you age. This can cause dry mouth, which can affect your sense of taste.
As you age, structures inside the ear start to change and their functions decline. Your ability to pick up sounds decreases – particularly in the high frequencies. You may also have trouble telling the difference between certain sounds or hearing a conversation when there is background noise. Persistent, abnormal ear noise (tinnitus) is another common problem in older adults.
With ageing, sensations may be reduced or changed due to decreased blood flow to the nerve endings or to the spinal cord or brain. The spinal cord transmits nerve signals and the brain interprets these signals. Slower transmission and diminished number of cells produces slower reaction times which affects perception, memory and soundness of reflexes.
Health problems, such as a lack of certain nutrients, can also cause sensation changes. Brain surgery, problems in the brain, confusion, and nerve damage from injury or chronic diseases such as diabetes can also result in sensation changes.
Examples of changed sensations include decreased temperature sensitivity, reduced ability to detect vibration, touch, and pressure. After age 50, many people have reduced sensitivity to pain or they may feel and recognize pain, but it does not bother them.
Older people may develop problems walking because of reduced ability to perceive where their body is in relation to the floor. This increases the risk of falling which is a common problem for older people.
So these are the gloomy facts… However, we can take a positive spin on these and ensure that we create environments to support changes to the senses so the negative effects of ageing are minimised as much as possible. Part 3 next month will explain how!
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5. Bush, A. L. H., Lister, J. J., Lin, F. R., Betz, J., & Edwards, J. D. (2015). Peripheral Hearing and Cognition: Evidence from the Staying Keen in Later Life (SKILL) Study. Ear and Hearing, 36(4), 395–407. http://doi.org/10.1097/AUD.0000000000000142
6. Attems J, Walker L, Jellinger K, A, Olfaction and Aging: A Mini-Review. Gerontology 2015;61:485-490