According to McPherson3, people generally attain full physical maturity and their maximal levels of energy and strength sometime in their early 20s, after which there is gradual and progressive decline in the structure and function of the body’s various components. Again, the important points here are that there is tremendous individual variability in the rates in which these declines take place, and the declines, in normal aging, are very, very gradual. Also, there is a strong correlation between a person’s physical exercise or activity level and his or her level of physical and mental health.
The following is a very brief summary of normal, age-related physical and sensory changes.4
Central nervous system (CNS)
The CNS begins to slow down with age, which means that reaction or response times become slower, fatigue sets in sooner, hand tremors may appear, and certain tasks may be performed more slowly (but likely just as well as before).
There are decreases in strength and endurance (although the rate and degree of loss in these areas seems to be highly correlated with the frequency and intensity of the person’s activity level over time); declines in the muscular system increase the chances of falls.
There are decreases in the maximum heart rate attainable and increases in blood pressure. These factors combine to hasten the onset of fatigue. As well, arteriosclerosis (―hardening of the arteries‖) and atherosclerosis (hardening and narrowing of the arterial walls), though not aspects of normal aging, are nevertheless common age-related diseases that are more prevalent in men than women.
The respiratory system experiences decreases in efficiency, which in turn decreases intake and transportation of oxygen to organs and muscles. Again, this means that older people tend to experience fatigue following physical activity, which may have implications for recreational and social activities.
Normal age-related changes to the structure and function of the eye include a thickening of the lens and a decrease in the diameter of the pupil, both of which limit the amount of light that reaches the retina. This means that older people generally require more light when reading or undertaking other activities. There also is less flexibility in the lens (presbyopia), which limits a person’s ability to focus on objects at varying distances, and decreases in a person’s ability to adapt to darkness, glare, and rapidly changing light levels. In addition, with age many people lose the ability to detect or differentiate between blue, green and violet tones. While none of these normal age-related changes are fully disabling, they can be upsetting to the individual and disruptive to everyday life activities.
At the same time, normal age- related vision changes must be distinguished from age-related eye diseases. Four major eye diseases frequently afflict older people: cataracts, glaucoma, macular degeneration and diabetic retinopathy5. Of these, cataracts are most common. Indeed, just about everyone over the age of 65 has some degree of cataracts, although for most people they are mild and aren’t painful. Cataracts occur when the transparent lens of the eye becomes filmy. For people who have them, cataracts feel like they are looking through a cloud or as though their eyeglasses were daubed with Vaseline. Because cataracts are so common and affect vision in a progressive manner, it may be easy to ignore them. But when cataracts affect vision to the point where the person can no longer undertake everyday tasks, it’s time to go to an ophthalmologist and consider cataract surgery.
As with normal age-related changes in vision, there is a gradual, progressive decline in people’s hearing as a result of aging. Because it is gradual, auditory impairment can be harder to detect, both for the person herself and for others; this can lead to communication problems. In contrast with normal, age-related hearing loss, presbycusis is a major hearing problem and ―the progressive inability to hear higher frequency sounds in music and speech‖ (McPherson, 1983, p.180). This condition most often occurs after age 50 and affects more men than women.
2 The material in this sub-section has been adapted from: Duncan, S. Family Matters: What is Normal Aging?, via: http://www.montana.edu/cpa/news/wwwpb-archives/home/aging.html
3 McPherson, B. (1983). Aging is a Social Process. Toronto: Butterworth and Co.
4 Adapted from McPherson (1983). Pp. 168-170 and 180-182.
5 Information in this sub-section adapted from “Chapter 3: Not-so-normal Aging: The Physical Side”. http://catalogue.pearsoned.co.uk/samplechapter/002863943X.pdf