The 1930s and the 1940s saw a great deal of scientific progress in the field of stress physiology after Selye dem-onstrated the effects of stress on rats. Scientists determined the main hormones released in response to stress were epinephrine, glucocorticoids and prolactin. Additional research uncovered the superb control mechanisms of the body that regulate the amount of these hormones released into the bloodstream. In engineering jargon there are multiple feedback domains for each hormone.
In lay terms, it means that the brain uses a variety of techniques to regulate the quantity of hormones. Sometimes, it measures the actual quantity of the hormone in the blood; at other times, it may use the rate of change of the hormone in the blood, etc. The body not only can sense something stressful, but is also amazingly ac-curate at measuring just how far and how fast the stressor is throwing the body out of allostatic balance.
The early scientific literature on stress is dominated by research in the engineering aspects of the stress response and the various feedback systems that are present. Unfortunately, for the scientists, some everyday examples opened up another set of factors that control stress response. Take an example of a small child getting an injection. The stress response can be fairly easily calculated and a neat mathematical model can explain it.
Now if the same child has a loving parent who will comfort it, the obvious result is that the child will show less of a stress response. The critical fact here is that body’s stress response (physiological response) can be controlled (modu-lated) by psychological factors. In other words, the stress response can be made bigger or smaller depending on purely psychological factors. Inevitably, the next step in this process was demonstrated—in the absence of any change in the physi-ological reality (i.e., no disruption in the allostasis of the body), purely psychological factors could trigger a stress response.
One of the early scientists to have discovered this phenomenon was Yale physiologist John Mason. He even proclaimed that all stress response was psychological. Obviously, there was a great deal of scientific debate about the nature of the stress response with Selye leading the group that said it was not purely psychological. In defence, they cited studies that showed that a stress response is generated among patients administered anesthesia during surgery immediately after the first incision is made. The current consensus is that some psychological factors can modulate the stress response.
The above paragraph discussed a very powerful concept from the point of view of the person suffering from stress. If we can identify the psychological factors that affect stress response, we can put those in practice and avoid thetrouble caused by it. At first glance, it might seem that determining the psychological factors involved in stress response might be a mushy, touchy-feely field of psychologists and therapists. But that is not the case and a solid body of elegant scientific experiments were used to identify the psychological factors. We will take a look at some of those experiments and see how they can help us in formulating coping strategies.
In one of the experiments, a rat received a mild electric shock (comparable to a human being receiving a static shock from a silk material or woollen carpet during winter). Over a series of these shocks the rat develops a prolonged stress response—its heart rate and glucocorticoids secretion go up, the probability of getting ulcer soars and a number of other diseases afflict the rat.
A second rat gets the same set of shocks—same intensity, duration and frequency. Its body is thrown out of allostasis to the same extent as the first rat. The only difference is that the second rat has a small piece of wood to chew on. Every time, it gets a shock, it can run to the wood and gnaw on it. The rat shows a low stress response. In the actual experi-ment, the scientists were examining the probability of getting ulcers. For the rat with a piece of wood to gnaw on, the probability of getting ulcers was dramatically lower than the one with no wood.
The second rat had an outlet for frustration. Other types of outlets work as well—let the stressed rat eat something, drink something or sprint on a running wheel and the likelihood of developing ulcers drops. We humans deal better with stressors when we have an outlet for our frustration. We are smart enough to imagine some of those outlets and get some relief. We are all familiar with the anecdotes of prisoners of war who spend hours imagining their favourite hobby to alleviate the prolonged and stressful period of captivity.
Another facet of this outlet for frustration was uncovered in experiments where the stressed rat could bite a smaller rat. To put it in scientific jargon, the rat shows stress-induced displacement aggression. The fact is that it works amazingly well in reducing the stress response of the rat receiving the shock. In fact, such displacement aggression is a real primate speciality. Baboons, monkeys and a host of other animals demonstrate the same stress-induced aggression towards weaker, lower ranked animals.
Depressingly, we humans are good at it too. Fortunately for the human race, a better strategy than beating up smaller persons is that of social networking. It helps to have a shoulder to cry on, a hand to hold, a loved one to listen to you, someone to hug you and tell you that it will be all right. In another series of subtle studies, volunteers were exposed to various stressors—giving a public speech, or perform mental arithmetic in a noisy and crowded area, arguing with strangers—with or without a supportive friend present.
In all cases, social support translated into less of a cardiovascular stress response. Persistent differences in degrees of social support can influence human physiology as well. For example, within the same family, stepchildren exhibit higher levels of stress hormones than among the biological children.
The studies on rats were performed with another set of controls. The rat gets the same shocks as before. However, before each shock, it hears a warning bell. Not surprisingly, the rate of ulcers drops. There is now predictability as to when the rat is administered an electric shock. It is not so much that the predictability helps reduce the effects of the shock but it allows the rat to rest and relax between the shocks. As another variant on the helpfulness of predictability, organisms will eventually get used to a stressor if it is applied over and over. The typical example given is that of army recruits as they learn to jump from a plane with a parachute. At the start of the training, the anticipatory stress response is very high. By the end of the training, the response is almost nonexistent.
We will see in a later section, the use of this technique to reduce anxiety and fear. Another experiment reveals an interesting facet of predictability. A rat is given small amounts of food at regular intervals. The rat eats it happily and in scientific terms it is called intermittent reinforcement schedule. Next, the pattern of delivery is changed from regular to random. The same amount of food is delivered over the course of time but the interval between deliveries is random. The rat experiences a stress response. There is not a single stressful thing going on in the rat’s life. In the absence of any stressor, loss of predictability triggers a stress response.
There are even circumstances in which people subjected to a lower state of a stressor can experience higher incidence of stress-related disease due to unpredictability. It would be easy to design an experiment with rats to prove this point. Unfortunately, a human version of this scenario took place during the World War II. In that instance, the Nazis bombed London with clockwork regularity every night. The suburb of London received a lot less bombing but it was very irregular (a high degree of unpredictability). It turns out that the ulcer rates were far higher in the suburbs than in London. An interesting postscript to this story—the ulcer rates dropped to pre-war levels after a few months of bombing! We have heard of stories of prisoners awaiting execution who demand an end to their appeals to higher courts to avoid the uncertainty. It seems like the waiting and unpredictability is worse than death!
Continuing with our rat studies, another related facet of psychology could be demonstrated. Give a rat a series of shocks as before. This time, use a rat that has been trained to press a lever to avoid the shock. Take away the lever, shock it, and the rat develops a massive stress response and major ulcers develop. Give the rat a lever to press even though it has been disconnected from the shock mechanism and it still helps. Down goes the stress response. Thus, the exercise of control is not critical; rather it is the belief that you have the control.
Some researchers have pointed out that loss of predict-ability and loss of control share a common element—novelty. Others have emphasized that these types of stressors cause arousal and vigilance, as you search for the new rules of pre-dictability and control. I think both these views are just different aspects of the same set of issues.
As we saw above, there are some powerful psychological factors that can trigger a stress response on their own, or make another stressor seem more stressful—loss of control or predictability, loss of outlet for frustration or source of support, or a perception that things are getting worse. These factors help in partly explaining how we all go through life full of stressors, yet differ so dramatically in our response to them. In engineering terms, it is as if we differ in the psychological factors through which we perceive the stressors in our world.
The experiments discussed above provide the foundation for formulating strategies to cope with stress. The strategies will involve some or all of these psychological variables, depending on the person and the stressor but they will help in reducing the ill-effects of the stress response.