Cortisol and Aging
Although you can't do anything about your age, it is probably important to discuss the differences in stress response between younger and older people. In very general terms, it appears to be true that as we age, we become less able to deal effectively with stress. This means that for the same "load" of stress, whether from exercise, illness, emotions, or whatever, a younger person will tend to "deal better" with the stressor compared to an older person. The primary difference does not seem to be much of a difference in the initial response to the stressor; old folks tend to secrete just as many stress hormones as their younger counterparts (though older folks also tend to have higher cortisol levels even under normal, nonstressed conditions). Instead, younger subjects tend to recover faster from stress, so they're able to get their cortisol levels back to within normal ranges in a much shorter period of time compared to older subjects. Being able to quickly turn off the stress response following the removal of a given stressor also appears to be associated with a slower growth of cancer cells (tumors), so the youngsters appear to have an edge when it comes to fending off cancer (at least in lab rats).
To better understand the relationship between cortisol and aging, let's consider the situation of the salmon. You probably know the basics of the story: The salmon swims upstream for thousands of miles, spawns, and quickly dies. (Some life!) If you were to catch a salmon right after spawning, you'd see a few interesting things, such as a poor immune system, lots of infections, unhealed wounds, stomach ulcers, etc. Sounds like an overactive stress response—and that's exactly what it is. Marine biologists have studied the physiology of spawning salmons to find that, lo and behold, they have outrageously high cortisol levels. Take it one step further and remove the adrenal glands from these salmon, and guess what happens? Having no adrenal glands means that the salmon experience no cortisol secretion and no rapid onset of death; they live on perfectly well for another year or so (which is quite a long time for a fish). The primary reason why cortisol levels go completely crazy in salmon is that they rapidly develop an inability to regulate their cortisol secretion. For some reason, their bodies fail to recognize the fact that they have plenty of cortisol in their system, so the adrenals just keep churning out more and more—and every organ system quickly deteriorates. A similar age-related breakdown in the regulation of cortisol secretion occurs in other animals, including mice, rats, dogs, monkeys, baboons, and humans (though none quite as dramatically as in the salmon).
One of the most exciting findings in the last few years of stress research has been that made by scientists at the University of California at San Francisco. Researchers in the Department of Psychiatry there have shown a distinct link between psychological stress and accelerated rates of aging in humans. For years, we've known that stress causes rodents, worms, and baboons to age faster, but this is the first direct evidence we have to indicate faster aging in stressed people—and, as you might expect, increased rates of high cholesterol, high blood pressure, high blood sugar, and greater abdominal obesity.
In a study of teachers in Finland, older teachers (average age fifty-four) were found to have much higher cortisol exposure and elevated blood pressure compared to younger teachers (average age thirty-one). The difference in cortisol levels was found to be due to the older teachers' inability to "recover" from high levels of job stress. Both younger and older groups had high cortisol levels at work, but only the younger teachers showed a reduced cortisol level after work. Stanford University psychiatrists have shown that caregivers of chronically ill patients (whether professional or family caregivers) have significantly higher levels of cortisol, which may be related to development of mental dysfunction in later life.
Italian researchers have shown that the older we get, the more cortisol we have, and the worse memory. These researchers have indicated that the cortisol/age/memory relationship is largely due to cortisol's tendency to shrink an area of the brain called the hippocampus, which has a high level of cortisol receptors and is involved in memory. Not only did levels of cortisol in the research subjects grow higher with age, but levels of testosterone fell, leading to a "double-whammy" detrimental effect on brain function with age. British researchers from the Birmingham University Medical School have also shown that as cortisol levels go up and testosterone levels fall with age and stress, immune function also falls, leading to an increase in infection rates in stressed elderly people.
So does this mean we're all destined to succumb to cortisol-related organ failure as we age? Certainly not. Making some of the right choices in terms of exercise regimen, dietary intake, sleep patterns, and the judicious use of nutritional supplements can go a long way toward retarding some of what we now view as "age-related" changes in how our bodies work and how we look and feel.
Whew! If the preceding information doesn't stress you out (even a little bit), then you haven't been reading very closely. At first glance, many of us might view the close relationship between stress, cortisol, and the long list of chronic diseases as a hopeless disaster just waiting to happen—and for a great many people, it is. The good news, however, is that armed with the right information and the proper motivation, one can do a great deal to counteract these potential problems. The general idea is to control the stress response in such a way that cortisol levels are maintained within their optimal range—not too high and not too low—with long-term health and wellness as the outcome. The rest of the book shows you how.