One of the questions we posited at the start of this chapter was the ability of older individuals to deal with stress. The short answer is that they deal poorly with stress and the long answer is the rest of this section. The inability of older individuals to deal effectively with stress fits in with our intuition and observation of aged persons as vulnerable and fragile. To put it in perspective, almost all the systems of the body of older people work as they do for young people. But bring in a stressor1 and the aged organism is likely to fail. Consider the scenario of an individual stressed by a sudden drop in temperature.
It takes longer for the older individual to regain normal temperature than a younger one. This takes us back to our definition of stress as anything that causes the body to be thrown out of allostasis; it seems older individuals take longer to regain allostasis than younger ones. In other studies, scientists measured the performance of different individuals in taking tests. The results are the same in the absence of stress. If the same tests are administered under stressful conditions (in noisy surroundings, under severe time pressure, etc.), the performance of old and young persons declines.
The thing to note is that the performance drops to a greater extent in the older person. The reason for this poor performance seems to be the lack of sufficient stress response. All the hormonal systems of the stress response have problems and the net result is that the older individuals cope poorly with stress. In some cases, there is enough hormonal secretion but the various cells are not responding to that signal.
The stress response in the older individual usually continues even after the stressor has finished. It takes longer for the body to return to normal after the stressful period. This has been observed in many animal studies—stress young and old individuals and they may have roughly the same stress response. In the case of the older individual, it takes longer for the system to return to normal. It should be clear that secreting stress hormones in the absence of a stressor is a generally bad idea and can lead to many of the problems that we have discussed so far.
Older individuals have higher levels of stress-response hormones even in their normal resting state. The levels of epinephrine and norepinephrine are higher in older individuals in their resting states. Do older individuals pay the price for having their stress response turned on even during their rest time? The answer is yes. For example, the higher blood pressure seen in many older people can be linked to the higher levels of epinephrine and norepinephrine.