by John Coates
Perhaps the most harmful effect of prolonged stress is the chronically raised heart rate and blood pressure, a condition known as hypertension. The unceasing pressure on arteries that comes with hypertension can cause small tears in arterial walls, tears which then attract healing agents called macrophages or, more commonly, white blood cells. Mounds of these sticky clotting agents grow over the arterial injuries, and subsequently trap passing molecules, like fats and cholesterol. Larger and larger plaques form, which can become calcified, a condition known as atherosclerosis, or hardening of the arteries. As the plaques grow and block arteries, they decrease blood flow to the heart itself, causing myocardial ischemia, or angina, a recurring pain in the chest. If the plaques become large enough they may break off, producing a thrombus, or clot, which then travels downstream to smaller and smaller arteries, and ends up blocking an artery to the heart, causing a heart attack, or an artery to the brain, causing a stroke.
As the economic crisis deepens, cortisol’s catabolic effects add to the problems created by high blood pressure. Insulin, which normally withdraws glucose from our blood for storage in cells, has been inhibited for months now, so high levels of glucose and low-density lipoproteins, the so-called bad cholesterol, course through traders’ arteries. Muscles as well get broken down for their nutrients, and the resulting amino acids and glucose circulate needlessly in the blood, looking for an outlet in demanding physical struggle. Our stress response is designed to fuel a muscular effort, yet the stress most of us now face is largely psychological and social, and we endure it sitting in a chair. The unused glucose ends up being deposited around the waist as fat, the type of fat deposit posing the greatest risk for heart disease. At the extreme, stressed individuals, with elevated glucose and inhibited insulin, can become susceptible to abdominal obesity and type 2 diabetes. Patients suffering from Cushing’s syndrome epitomise the change in body shape, having atrophied arm and leg muscles and fat build-up on the torso, neck and face, making them appear much like an apple on toothpicks. A year into the financial crisis, the testosterone-ripped iron men of the bull market start to look decidedly puffy.
Heart disease caused by uncertainty and uncontrollability in the workplace has been amply documented. In a pioneering study of job stress, Healthy Work, Robert Karasek and Tores Theorell found that workers facing the highest levels of workload coupled with uncontrollability in their jobs suffered higher rates of hypertension, elevated cholesterol and heart disease, all signs of chronically elevated stress hormones. Similarly, in Britain, a series of studies called the Whitehall Studies looked at stress among civil servants, most notably in departments undergoing privatisation. The authors found that the employees most exposed to job insecurity suffered higher levels of cholesterol, higher rates of weight gain, and an increased incidence of stroke. Finally, epidemiological evidence exists of widespread damage that economic recessions wreak on the health of workers. A study conducted in Sweden with 40,000 people over a sixteen-year period found that health was strongly correlated with the business cycle, with mortality from cardiovascular disease, cancer and suicide all increasing during recessions.
Data on the financial industry is sparse, but private health insurance companies throughout the US and the UK reported a surge in claims for peptic ulcers, stress and depression after the credit crisis began in the autumn of 2007. In July 2008, for example, British United Provident Association Ltd, the UK’s largest private health insurer, reported that the number of employees from financial institutions seeking treatment for stress and depression had risen 47 per cent from a year earlier. The World Health Organisation also warned about the rise of mental-health problems and suicide with the advent of the credit crisis and the subsequent recession. Recently, a few years after the event, we are starting to get hard epidemiological data on the fallout from the Credit Crisis. One study has found that during 2007–09 there was a spike in the rate of heart attacks in London, and this occurred against a backdrop of a decreasing incidence of heart attacks in the rest of the UK. The authors estimate that this surge in heart attacks in London led to an additional 2,000 deaths, and resulted, they suggest, from the impact of the Credit Crisis on the financial district. A market crash may thus produce not only an economic disaster but also a medical one.
In the myriad ways described here, the stress response, as it builds and ramifies over the course of weeks and months, worsens the credit crisis. The bodily response initiated to handle the stress feeds back on the brain, causing anxiety, fear and a tendency to see danger everywhere. By so doing, this steroid feedback loop, in which market losses and volatility lead to risk-aversion and to a further sell-off in the market, can exaggerate a bear market and turn it into a crash. Body–brain interactions may thus shift risk preferences systematically across the business cycle, destabilising it. Economists and central bankers, such as Alan Greenspan, refer to an irrational pessimism upsetting the markets, just as John Maynard Keynes once spoke of the dimming of animal spirits. With the development of modern neuroscience and endocrinology we can begin to provide a scientific explanation for these colourful phrases: cortisol is the molecule of irrational pessimism.
PART IV
Resilience
EIGHT
Toughness
CAN WE CONTROL OUR STRESS RESPONSE?
Watching cortisol at work, as we have on our visit to Wall Street, enables us to see what many endocrinologists have long recognised: evolution has equipped us with a stress response that can be fatally dysfunctional in modern society. As it lingers and becomes chronic, as it so easily does with work-related or social problems, the stress response morphs from life saver to killer. It may have been engineered to carry us clear of immediate danger, but like the fire brigade, the stress response may save our house from an emergency only to destroy it with water damage. Indeed, chronic stress may be responsible for many of the most deadly and intractable problems faced by modern medicine – hypertension, heart disease, type 2 diabetes, immune disorders and depression.
Given what is at stake, for both personal health and the stability of the financial system, we have to ask: can we turn off the cortisol? Can we control its toxic body–brain feedback loop? Sadly the answer is: only with very great difficulty. Our conscious and rational selves have very little control over sub-cortical parts of the brain such as the amygdala, the hypothalamus and the brain stem. The trouble, as Joe LeDoux explains, is that we have a forest of axons (the fibres sending messages from a neuron) running up from our brain stem and our limbic system (the emotional brain) to our neo-cortex, ensuring that our rational efforts are regularly influenced by sub-cortical signals; but we have many fewer axons extending down into these primitive brain regions, so proportionally less conscious influence over them. Anyone who has experienced ungrounded panic attacks, or been in love with the wrong person, knows that efforts to consciously change our feelings are doomed to an endless cycle of repetition and failure.
An illuminating demonstration of the almost complete divorce between the conscious and unconscious expression of stress can be found in what is called an open field experiment conducted with rodents. When researchers put a rodent in an open field – a dangerous place, given its easy exposure to predators – it displayed classic symptoms of an animal stress response: freezing into immobility, defecation and elevated corticosterone (the rodent version of cortisol). However, if the researchers repeated this procedure for several days, the rodent gradually habituated to the experience. Nothing bad had happened yet, so the behavioural side of the stress response abated; the rodent stopped freezing and defecating. Interestingly, though, its corticosterone levels remained stubbornly elevated. The rodent was no longer consciously registering stress, yet its hormones were.
Now ask yourself: which of these two responses, the behavioural or the physiological, is more appropriate to the situation? Well, a rodent should not be in an open field – an objectively dangerous place for it – so it should indeed be stressed. And, remarkably
, its adrenal glands know this even if its conscious brain does not.
We found much the same thing with the traders we were studying. In the chapter on gut feelings I described an experiment in which we sampled cortisol from traders and asked them through a questionnaire how stressed they were by their P&L or by the markets. Their answers turned out to have little if anything to do with losing money, large swings in their P&L or high volatility in the market; yet their cortisol levels did faithfully track these stressors. Our findings illustrated just how disconnected the conscious and unconscious stress responses can be, how people often invent stories to accompany their behaviour. By means of these stories we may even persuade ourselves we are not stressed, or talk ourselves into feeling better about our plight. Yet if our objective situation remains novel, uncertain or uncontrollable, our physiology will remain on high alert, and in time our health will suffer. The hypothalamus and the adrenal glands appear to respond more to objective cues than to an encouraging chat. Their pathologies may not be amenable to a talking cure.
Despite this seemingly bleak conclusion, research into the physiology of the stress response holds out more promise than discouragement. First, by allowing us to see that stress is largely a physiological preparation for physical action, this research raises the possibility of training our physiology so that we develop a greater mental and physical stamina, toughening us against the fatigue, anxiety and psychiatric disorders that follow from chronic stress. Such a possibility may sound futuristic, yet there is a field of science that has already made remarkable breakthroughs in designing just such toughening regimes, and that is sports science. Second, by allowing us to see that stress emerges from objective circumstances, the research raises the possibility of changing these circumstances, changes which could then filter through to our mental state and our physical health. Let us consider in turn these two approaches to mitigating chronic stress: physiological toughening and objective changes in the workplace.
THE TOUGHENED INDIVIDUAL
Physical toughness is today relatively well understood. Sports scientists have made great advances in their understanding of strength, posture, coordination and endurance. Mental toughness, by comparison, has received far less attention, and remains accordingly less well understood. This is unfortunate. Work today relies less on physical effort and more and more on mental effort, and with this change has come a greater number of work days lost to anxiety, mental fatigue, stress and depression.
The research that does exist on mental toughness, coming from physiology, neuroscience and sports medicine, nonetheless offers some tantalising suggestions. To begin with, mental toughness involves a particular attitude to novel events: a toughened individual welcomes novelty as a challenge, sees in it an opportunity for gain; an untoughened individual dreads it as a threat and sees in it nothing but potential harm. What is intriguing about the research into toughness is the finding that to each of these attitudes – viewing novelty as a challenge or as a threat – there corresponds a distinctive physiological state.
Medical researchers and sports scientists have studied the differences between these physiological states in order to answer a number of medically important questions. What neuro-chemical profile characterises a person who can cope effectively even when scared? Why can some people maintain low levels of anxiety even when faced by uncontrollable stressors? And what balance of hormones and neuromodulators enables some people to remain motivated even in an environment lacking rewards(perhaps an environment like a financial crisis)? Medical researchers believe that finding answers to these questions will help them mitigate the effects of chronic stress, diagnose and prevent depression, and understand and treat conditions such as post-traumatic stress disorder, a debilitating syndrome affecting war veterans and people who have suffered personal trauma in which they vividly and uncontrollably relive their terrors.
Some scientists, recognising that mental toughness corresponds to a physiological profile, have gone a step further and asked, can this toughness be trained? Can purely physical training regimes translate into emotional stability, mental endurance and improved cognitive performance? Scientists who think the answer is ‘yes’ have built their research upon a curious finding – that resilience to stress comes from experiencing stress.
This idea originated in a lab at Rockefeller run by a psychologist named Neal Miller. Miller was one of the fathers of what is called behavioural medicine, the idea that behavioural therapy can rewire our brain and rebuild our body just as thoroughly as many medications. He and his lab also conducted some pioneering experiments in the physiology of stress. It was in Miller’s lab that two of his students, Bruce McEwen and Jay Weiss, discovered cortisol receptors in the brain, and in the process described the hormone feedback loops between brain and body which, I have suggested, may be influential in the financial markets. Miller also made some of the first discoveries about toughening. In particular, he and Weiss found that when rats were exposed to chronic (in other words unrelenting) stress they came to suffer both physical illness and learned helplessness, and these were the result of depleted noradrenalin levels in their brains. However, if the rats were exposed to acute (in other words short-lived) stress, even if it was repeated over and over, they emerged with a hardier physiology and an increased immunity to the damaging effects of further stressors. These findings, initially surprising, enabled scientists to see that the process of mental toughening bears similarities to that of physical toughening.
Sports scientists know, for instance, that to build lean-muscle mass and expand aerobic capacity athletes must endure a training process that shocks their muscles and taxes their cardiovascular systems, to the point of inflicting mild damage to tissues, and then punctuate this process with periods of rest and recovery. Stress, recovery, stress, recovery – when calibrated to exhaust an athlete’s resources, but only just, and then replenish them, the process can expand the productive capacity of a broad range of cells in the athlete’s body. When coaches time this training regime just right they can tune their athletes so that they arrive on the day of competition with the optimal amount of glucose, haemoglobin, adrenalin, cortisol and testosterone coursing through their arteries. What the scientists studying toughening have found is that a somewhat similar process of challenge and psychological loading followed by recovery can tune our brain and nervous system so that we too approach stressors with resilience and an optimal mix of hormones, neuromodulators, and nervous-system activation.
What exactly does this resilience consist of? What is physiological toughness? And how do we achieve it? To describe the state of toughness and how the process of toughening works we should consider in turn each ingredient in its physiological cocktail: catabolic hormones; anabolic hormones; amines, the class of chemical which includes adrenalin, noradrenalin and dopamine; and the vagus nerve. Catabolic hormones. Sports scientists and medical doctors know that our catabolic mechanisms, such as cortisol-producing cells, must be kept on a short leash. To repeat, a catabolic hormone is one that breaks down energy stores, such as muscle, for immediate use. Cortisol, as mentioned, is thus crucial in supplying us with energy when we mount an all-out physical or mental effort, but it is in many ways too powerful, and should be administered sparingly. By breaking down muscles and converting them into immediately usable forms of energy, cortisol in effect strip-mines our body for nutrients. If it is not turned off quickly, after a few days, a couple of weeks at the most, our body begins to disintegrate under its caustic influence. We come to suffer, as surveyed in the previous chapter, a broad range of physical ailments, as well as anxiety and a tendency to view events as threats rather than challenges.
We need cortisol to deliver metabolic support when we are challenged, but we must prevent it from turning into some doomsday-like defence mechanism, saving us for the moment but guaranteeing long-term annihilation. Its production and release should therefore occur sporadically, much as it would in a well-timed training regime, and be followed by a
recovery period. A regular ebb and flow of catabolic hormones promotes health, but a continual flow kills.
Anabolic hormones. It is during our downtime, when catabolism is turned off, that anabolic hormones step in and rebuild our depleted energy stores so that we have fuel to draw on next time we are called into action. These anabolic hormones include testosterone and growth hormone, which together convert amino acids into muscle and calcium into bone; insulin, which removes excess glucose from the blood and deposits it in the liver; and a chemical called insulin-like growth factor (IGF), which rejuvenates cells throughout the body and brain. A healthy person, and to a greater extent a tempered athlete, will have a high ratio of anabolic to catabolic hormones, a ratio known as the growth index. A high growth index indicates a robust capacity to rebuild one’s body after a period of destruction, a condition that Bruce McEwen, together with Elissa Epel and Jeannette Ickovics, has termed ‘ thriving’.
Without downtime our growth index declines, with the result that even a strenuous athletic training regime will fail to deliver results, the athletes finding to their frustration that their performance has gone stale. Older people may suffer a more serious decline in their growth index because they may stop producing testosterone and growth hormone altogether, while producing ever increasing amounts of cortisol; as a result they come to suffer what is called a ‘failure to thrive’, their high cortisol levels draining them of muscle and vitality. The simple ratio of testosterone to cortisol, easily assessed through either a saliva or a blood sample, can serve as a sensitive measure of our immunity to daily stress and our state of preparedness for competition. However, McEwen and colleagues recommend a slightly more complex measure, an index of the bodywide strain we experience when stressed. McEwen includes in this index blood pressure, body-mass index, hip-to-waist ratio, cholesterol levels, blood glucose levels, and noradrenalin and cortisol levels as sampled from urine. He has found that this index, more than any one of its components on its own, is a reliable predictor of future health.