Taste and Smell Lessen with Age

The senses of taste and smell are inextricably connected, and both can have a profound effect on appetite. In elderly persons, the neurological functions that govern these senses decrease with age as a result of age-related neuron loss, and the elderly lose the intensity of taste and smell that they possessed when younger. This can lead to a concomitant decline in appetite, which may lead to nutritional problems, reported the American researchers.

The scientists used an olfactometer to compare the abilities of college students and elderly people to detect and discriminate odours. The groups were matched as much as possible for background and socio-economic level, both of which can be important factors in familiarity with tastes and smells.

College students are able to detect an odour at much lower concentrations than are elderly people. This change in threshold affects eating not only because odour itself can stimulate appetite, but also because some people notice a bitter taste in foods that they are unable to smell. The scientists report that a significantly greater percentage of elderly persons complained of a bitter flavour in foods that tasted normal to younger subjects. For the elderly, this may mean that foods they once enjoyed no longer taste good.

A decreased sense of smell among elderly persons held true not only for food, but for less pleasant odours as well. The researchers tested their subjects with urine like odours, and found that aged subjects had even more difficulty detecting those odours than they did detecting the food smells. They believe that this may account for the tolerance in the elderly of the sometimes malodorous atmosphere of nursing homes and hospitals. Many younger persons say that they can't stand to work there because of the smell, although older residents seem unbothered.

The scientists also found that elderly persons lose the ability to discriminate between unlike tastes, as well as to identify familiar ones. They prepared foods to make them identical in consistency, and then tested them on blindfolded subjects. For elderly persons, things began to taste the same. The person might be able to detect a taste, but not be able to tell what it is. For example, only 55 percent of the elderly subjects recognized the taste of apple, while 61 percent of the college students identified it correctly. Many elderly persons prefer fruit flavours, however, because the ability to taste these flavours often lingers longer.

The explanation for this decline in sensory ability may lie in the fact that tastes are coded across neurons. For example, there is a difference in the codes for salty tastes and for bitter tastes. With age we drop neurons, and so with age there is less difference between the two patterns. If a person needed a total neural mass of, say ten, to detect taste, he may need a larger mass to discriminate between tastes.

12. Pick out the words from the text, which may be grouped under the heading "Senses".

13. Give Ukrainian equivalents of:

to be inextricably connected; to have a profound effect; elderly people; a concomitant decline; age-related neuron loss; to detect and discriminate odours; nutritional problems; threshold; nursing home; a greater percentage; identical in consistency; blindfolded subjects; fruit flavours; sensory ability; bitter tastes; a total neural mass.

14. Answer the following questions:

1. Why do the neurological functions decrease in elderly persons?

2. What can it cause?

3. What experiment was made to discriminate odours?

4. What did the elderly people complain about?

5. What other ability do elderly people lose?

6. What flavours do they prefer?

7. How may it be explained?

8. What is the conclusion drawn by the researchers?