Somesthesia and Balance
Imagine that you are locked in an embrace with a lover right now. Think about how good it feels when you are caressed lovingly, the tingly sensations you get. You can thank your somesthetic system for that; without it, you probably wouldn’t bother. Remember Bertha, the older woman worried about falling? To maintain balance and avoid falls, your somesthetic system integrates a great deal of information about your body position.
Somesthesia. As you’ve probably discovered, a lover’s touch feels different on various parts of your body. That’s because the distribution of touch receptors is not consistent throughout the body; the greatest concentrations are in the lips, tongue, and fingertips. Although it takes more pressure with age to feel a touch on the smooth (nonhairy) skin on the hand such as the fingertips (Stevens, 1992), touch sensitivity in the hair-covered parts of the body is maintained into later life (Whitbourne, 1996a).
Older adults often report that they have more trouble regulating body temperature so that they feel comfortable. However, the research evidence to support this perception is conflicting. Some data suggest that the threshold for warmth increases somewhat (Whitbourne, 1996a). These data appear to conflict with lowered cold tolerance by older adults, which should create a much larger change in threshold. The discrepancy may be caused by different age effects between temperature sensitivity and temperature regulation, but we do not know for certain (Whitbourne, 1996a).
Sensations from the skin, internal organs, and joints serve critical functions. They keep us in contact with our environment, help us avoid falling, help us communicate, keep us safe, and factor into our perception of pain. In terms of self-esteem, how well our body is functioning tells us something about how well we are doing. Losing bodily sensations can have major implications; loss of sexual sensitivity and changes in the ability to regulate one’s body temperature affect the quality of life. How a person views these changes is critical for maintaining self-esteem. We can help by providing supportive environments that lead to successful compensatory behaviors. Despite years of research, we do not understand how or even whether our ability to perceive these sensations changes with age. Part of the problem has to do with how such sensations, including pain, are measured and how individual differences in tolerance affects people’s reports.
Balance. Bertha, the older woman we met in the vignette, as well as anyone riding a bicycle, is concerned about losing balance and falling. Bertha (and each of us) gets information about balance from the vestibular system, housed deep in the inner ear. The vestibular system is designed to respond to the forces of gravity as they act on the head and then to provide this information to the parts of the brain that initiate the appropriate movements so that we can maintain balance.
Dizziness (the vague feeling of being unsteady, floating, and light-headed) and vertigo (the sensation that one or one’s surroundings are spinning) are common experiences for older adults. Although age-related structural changes in the vestibular system account for some of the problems, they do not entirely account for increases in dizziness and vertigo. Also, it takes older adults longer to integrate all the other sensory information coming to the brain to control posture (Aldwin & Gilmer, 2004). And dizziness can be a side effect of certain medications and physical illnesses.
Because of these changes, the likelihood of falling increases with age, especially after age 70 (Vereeck et al., 2008). Falls may be life-threatening events for older adults, especially for those with osteoporosis, because of the increased risk of broken bones. Environmental hazards such as loose rugs and slippery floors are more likely to be a factor for healthy, community-dwelling older adults, whereas disease is more likely to play a role in institutionalized people. Increases in body sway, the natural movement of the body to maintain balance, occur with increasing age. Connections between the degree of body sway and likelihood of falling have been shown, with people who fall often having more body sway (El Haber et al., 2008).
Physical Changes 83