It was a regular Tuesday morning in New York City. University students were sitting in their morning classes. People were arriving at work and the streets were beginning to fill with shoppers and tourists. Then, at 8:46 a.m., American Airlines Flight 11 crashed into the North Tower of the World Trade Center. People watched in horror. How could this have happened? This seemed like a terrible accident. Then at 9:03 a.m., United Airlines Flight 175 crashed into the South Tower of the World Trade Center. There were then reports of a plane crashing into the Pentagon. And another somewhere in Pennsylvania. The terrorist attacks on the World Trade Center on September 11, 2001, were an enormous stressor that had a lasting impact on many people, physically and psychologically. People living close to the World Trade Center (within 2.4 km) during 9/11 were found to have less grey matter in the amygdala, hippocampus, insula, anterior cingulate, and medial prefrontal cortex relative to those living more than 322 km away during the attacks, suggesting that the stress associated with the attacks may have reduced the size of these parts of the brain that play an important role in emotion, memory, and decision making (Ganzel et al., 2008). Brain measurements were taken more than 3 years after 9/11: This tells us that the event had long-term consequences on brain structure. Children who watched more television coverage of 9/11 had greater symptoms of post-traumatic stress disorder than children who watched less coverage (Otto et al., 2007). People around the United States who had a stronger acute stress response to the events of 9/11 had a 53 percent increased incidence of heart problems over the next 3 years (Holman et al., 2008). Stress can produce changes in every system of the body and mind, stimulating both physical reactions and psychological reactions. Let us consider each in turn.

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Walter Cannon (1929) coined a phrase to describe the body’s response to any threatening stimulus: the fight-or-flight response, an emotional and physiological reaction to an emergency that increases readiness for action. The mind asks, “Should I stay and battle this somehow, or should I run like mad?” And the body prepares to react. If you are a cat at this time, your hair stands on end. If you are a human, your hair stands on end, too, but not as visibly. Cannon recognized this common response across species and suspected that it might be the body’s first mobilization to any threat.

Research conducted since Cannon’s discovery has revealed what is happening in the brain and body during this reaction. Brain activation in response to threat occurs in the hypothalamus, stimulating the nearby pituitary gland, which in turn releases a hormone known as ACTH (short for adrenocorticotropic hormone). ACTH travels through the bloodstream and stimulates the adrenal glands atop the kidneys (see FIGURE 14.1). In this cascading response of the HPA (hypothalamic–pituitary–adrenocortical) axis, the adrenal glands are stimulated to release hormones, including the catecholamines (epinephrine and norepinephrine), which increase sympathetic nervous system activation (and therefore increase heart rate, blood pressure, and respiration rate) and decrease parasympathetic activation (see the Neuroscience and Behaviour chapter). The increased respiration and blood pressure make more oxygen available to the muscles to energize attack or to initiate escape. The adrenal glands also release cortisol, a hormone that increases the concentration of glucose in the blood to make fuel available to the muscles. Everything is prepared for a full-tilt response to the threat.

What might have happened if the terrorist attacks of 9/11 were spaced out over a period of days or weeks? Starting in the 1930s, Hans Selye, a Canadian scientist working at Université de Montréal, undertook a variety of experiments that looked at the physiological consequences of severe threats to well-being. He subjected rats to heat, cold, infection, trauma, hemorrhage, and other prolonged stressors, making few friends among the rats or their sympathizers, but learning a lot about stress. His stressed-out rats developed physiological responses that included an enlarged adrenal cortex, shrinking of the lymph glands, and ulceration of the stomach. Noting that many different kinds of stressors caused similar patterns of physiological change, he called the reaction the general adaptation syndrome (GAS), which he defined as a three-stage physiological stress response that appears regardless of the stressor that is encountered. The GAS is nonspecific; that is, the response does not vary, no matter what the source of the repeated stress.

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None of this is very good news. Although Friedrich Nietzsche once said, “What does not kill me makes me stronger,” Selye found that severe stress takes a toll on the body. He saw the GAS as occurring in three phases (see FIGURE 14.2):

Right now, you are (we hope!) enjoying years of healthy living. Unfortunately, as people age, the body slowly begins to break down (just ask any of the authors of this book). Interestingly, recent research has revealed that stress significantly accelerates the aging process. Elizabeth Smart’s parents noted that, upon being reunited with her after 9 months of separation, they almost did not recognize her because she appeared to have aged so much (Smart, Smart, & Morton, 2003). Theirs is an extreme example; you can see examples of the effects of stress on aging around you in everyday life. People exposed to chronic stress, whether due to their relationships, job, or something else, experience actual wear and tear on their bodies and increased aging. Take a look at the pictures of the past three Canadian prime ministers before and after their terms as prime minister (arguably, one of the most stressful jobs in the world). As you can see, they appear to have aged much more than the 4 to 10 years that passed between their first and second photographs. How exactly can stressors in the environment increase the aging process?

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Understanding this process requires knowing a little bit about how aging occurs. The cells in our bodies are constantly dividing, and as part of this process, our chromosomes are repeatedly copied so that our genetic information is carried into the new cells. This process is facilitated by the presence of telomeres, caps at the ends of each chromosome that protect the ends of chromosomes and prevent them from sticking to each other. They are kind of like the tape at the end of your shoelaces that keeps them from being frayed and not working as efficiently. Each time a cell divides, the telomeres become slightly shorter. If they become too short, cells can no longer divide and this can lead to the development of tumours and a range of diseases. Fortunately, our bodies fix this problem by producing a substance called telomerase, an enzyme that rebuilds telomeres at the tips of chromosomes. As cells repeatedly divide over the course of our lives, telomerase does its best to re-cap our chromosomes with telomeres. Ultimately, in the end, telomerase cannot keep up telomere production at a sufficient pace, and over time cells lose their ability to divide, causing aging and in the end, cell death. The recent discovery of the function of telomeres and telomerase and their relation to aging and disease by Elizabeth Blackburn and colleagues has been one of the most exciting advances in science in the past several decades.

Interestingly, social stressors can play an important role in this process. People exposed to chronic stress have shorter telomere length and lower telomerase activity (Epel et al., 2004). Laboratory studies suggest that cortisol can reduce the activity of telomerase, which in turn leads to shortened telomeres, which has downstream negative effects in the form of accelerated aging and increased risk of a wide range of diseases including cancer, cardiovascular disease, diabetes, and depression (Blackburn & Epel, 2012). This sounds dire, but there are things that you can do to combat this process and potentially live a healthier and longer life! Activities like exercise and meditation seem to prevent chronic stress from shortening telomere length, providing a potential explanation of how these activities may convey health benefits such as longer life and lower risk of disease (Epel et al., 2009; Puterman et al., 2010).

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The immune system is a complex response system that protects the body from bacteria, viruses, and other foreign substances. The system includes white blood cells, such as lymphocytes (including T cells and B cells), that produce antibodies that fight infection. The immune system is remarkably responsive to psychological influences. Psychoneuroimmunology is the study of how the immune system responds to psychological variables, such as the presence of stressors. Stressors can cause hormones known as glucocorticoids to flood the brain (described in the Neuroscience and Behaviour chapter), wearing down the immune system and making it less able to fight invaders (Webster Marketon & Glaser, 2008).

For example, in one study, medical student volunteers agreed to receive small wounds to the roof of the mouth. Researchers observed that these wounds healed more slowly during exam periods than during summer vacation (Marucha, Kiecolt-Glaser, & Favagehi, 1998). In another study, a set of selfless, healthy volunteers permitted researchers to swab the common cold virus in their noses (Cohen et al., 1998). You might think that a direct application of the virus would be like exposure to a massive full-facial sneeze and that all the participants would catch colds. The researchers observed, though, that some people got colds and others did not—and stress helped account for the difference. Volunteers who had experienced chronic stressors (lasting a month or longer) were especially likely to suffer colds. In particular, participants who had lost a job or who were going through extended interpersonal problems with family or friends were most susceptible to the virus. Brief stressful life events (those lasting less than a month) had no impact. So if you are fighting with your friends or family, best to get it over with quickly; it is better for your health.

The effect of stress on immune response may help to explain why social status is related to health. Studies of British civil servants beginning in the 1960s found that mortality varied precisely with civil service grade: the higher the classification, the lower the death rate, regardless of cause (Marmot et al., 1991). One explanation is that people in lower-status jobs more often engage in unhealthy behaviour such as smoking and drinking alcohol, and there is evidence of this. But there is also evidence that the stress of living life at the bottom levels of society increases risk of infections by weakening the immune system. People who perceive themselves as low in social status are more prone to suffer from respiratory infections, for example, than those who do not bear this social burden—and the same holds true for low-status male monkeys (Cohen, 1999).

The heart and circulatory system are also sensitive to stress. For example, for several days after Iraq’s 1991 missile attack on Israel, heart attack rates went up markedly among citizens in Tel Aviv (Meisel et al., 1991). The full story of how stress affects the cardiovascular system starts earlier than the occurrence of a heart attack: Chronic stress creates changes in the body that increase later vulnerability.

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The main cause of coronary heart disease is atherosclerosis, a gradual narrowing of the arteries that occurs as fatty deposits, or plaque, build up on the inner walls of the arteries. Narrowed arteries result in a reduced blood supply and, eventually, when an artery is blocked by a blood clot or detached plaque, in a heart attack. Although smoking, a sedentary lifestyle, and a diet high in fat and cholesterol can cause coronary heart disease, chronic stress also is a major contributor (Krantz & McCeney, 2002). As a result of stress-activated arousal of the sympathetic nervous system, blood pressure goes up and stays up, and this gradually damages the blood vessels. The damaged vessels accumulate plaque, and the more plaque, the greater the likelihood of coronary heart disease. For example, a large study of Finnish men age 42 to 60 found that those who exhibited elevated blood pressure in response to stress and who reported that their work environment was especially stressful showed progressive atherosclerosis of a major artery in the neck during the 4-year study (Everson et al., 1997).

In the 1950s, cardiologists Meyer Friedman and Ray Rosenman (1974) conducted a revolutionary study that demonstrated a link between work-related stress and coronary heart disease. They interviewed and tested 3000 healthy middle-aged men and then tracked their subsequent cardiovascular health. Based on their research, Friedman and Rosenman developed the concept of the Type A behaviour pattern, which is characterized by a tendency toward easily aroused hostility, impatience, a sense of time urgency, and competitive achievement strivings. They compared Type A individuals to those with a less driven behaviour pattern (sometimes called Type B). The Type A men were identified not only by their answers to questions in the interview (agreeing that they walk and talk fast, work late, set goals for themselves, work hard to win, and easily get frustrated and angry at others), but also by the pushy and impatient way in which they answered the questions. They watched the clock, barked back answers, and interrupted the interviewer, at some points even slapping him with a fish. Okay, the part about the fish is wrong, but you get the idea: These people were intense. The researchers found that of the 258 men who had heart attacks in the 9 years following the interview, over two thirds had been classified as Type A and only one third had been classified as Type B.

A later study of stress and anger tracked medical students for up to 48 years to see how their behaviour while they were young related to their later susceptibility to coronary problems (Chang et al., 2002). Students who responded to stress with anger and hostility were found to be three times more likely to later develop premature heart disease and six times more likely to have an early heart attack than were students who did not respond with anger. Hostility, particularly in men, predicts heart disease better than any other major causal factor, such as smoking, high caloric intake, or even high levels of LDL cholesterol (Niaura et al., 2002) (see also FIGURE 14.3). Stress affects the cardiovascular system to some degree in everyone, but is particularly harmful in those people who respond to stressful events with hostility.

The body’s response to stress is intertwined with responses of the mind. Perhaps the first thing the mind does is try to sort things out—to interpret whether an event is threatening or not—and if it is, whether something can be done about it.

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The interpretation of a stimulus as stressful or not is called primary appraisal (Lazarus & Folkman, 1984). Primary appraisal allows you to realize that a small dark spot on your shirt is a stressor (spider!) or that a 113-km/h drop from a great height in a small car full of screaming people may not be (roller coaster!). In a demonstration of the importance of interpretation, researchers used a gruesome film of a subincision (a kind of genital surgery that is part of some tribal initiation rites) to severely stress volunteer participants (Speisman et al., 1964). Self-reports and participants’ autonomic arousal (heart rate and skin conductance level) were the measures of stress. Before viewing the film, one group heard an introduction that downplayed the pain and emphasized the coming-of-age aspect of the initiation. This interpretation markedly reduced the film viewers’ stress compared with another group whose viewing was preceded by a lecture accentuating the pain and trauma.

The next step in interpretation is secondary appraisal, determining whether the stressor is something you can handle or not; that is, whether you have control over the event (Lazarus & Folkman, 1984). Interestingly, the body responds differently depending on whether the stressor is perceived as a threat (a stressor you believe you might not be able to overcome) or a challenge (a stressor you feel fairly confident you can control) (Blascovich & Tomaka, 1996). The same midterm exam is seen as a challenge if you are well prepared, but a threat if you did not study. Fortunately, interpretations of stressors can change them from threats to challenges. One recent study (Jamieson et al., 2010) showed that instructing students to reframe their anxiety about an upcoming exam as arousal that will help them on the test actually boosted their sympathetic arousal (signalling a challenge orientation) and improved test performance. Remember this technique next time you are feeling anxious about a test: Increased arousal can improve your performance!

Although both threats and challenges raise heart rate, threats increase vascular reactivity (such as constriction of the blood vessels, which can lead to high blood pressure). In one study, researchers found that even interactions as innocuous as conversations can produce threat or challenge responses depending on the race of the conversation partner. Asked to talk with another, unfamiliar student, white students showed a challenge reaction when the student was white and a threat reaction when the student was African American (Mendes et al., 2002). Similar threat responses were found when white students interacted with an unexpected partner, such as an Asian student who had an accent characteristic of the American South (Mendes et al., 2007). It is as if social unfamiliarity creates the same kind of stress as lack of preparedness for an exam. Interestingly, having previously interacted with members of an unfamiliar group tempers the threat reaction (Blascovich et al., 2001).

Did you ever take a class from an instructor who had lost interest in the job? The syndrome is easy to spot: The teacher looks distant and blank, almost robotic, giving predictable and humdrum lessons each day, as if it does not matter whether anyone is listening. Now imagine being this instructor. You decided to teach because you wanted to shape young minds. You worked hard, and for a while things were great. But one day, you looked up to see a room full of miserable students who were bored and did not care about anything you had to say. They updated their Facebook pages while you talked and started shuffling papers and putting things away long before the end of class. You are happy at work only when you are not in class. When people feel this way, especially about their jobs or careers, they are suffering from burnout, a state of physical, emotional, and mental exhaustion created by long-term involvement in an emotionally demanding situation and accompanied by lowered performance and motivation.

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Burnout is a particular problem in the helping professions (Maslach, Schaufeli, & Leiter, 2001). Teachers, nurses, clergy, doctors, dentists, psychologists, social workers, police officers, and others who repeatedly encounter emotional turmoil on the job may only be able to work productively for a limited time. Eventually, many succumb to symptoms of burnout: overwhelming exhaustion, a deep cynicism and detachment from the job, and a sense of ineffectiveness and lack of accomplishment (Maslach, 2003). Their unhappiness can even spread to others; people with burnout tend to become disgruntled employees who revel in their coworkers’ failures and ignore their coworkers’ successes (Brenninkmeijer, Vanyperen, & Buunk, 2001).

What causes burnout? One theory suggests that the culprit is using your job to give meaning to your life (Pines, 1993). If you define yourself only by your career and gauge your self-worth by success at work, you risk having nothing left when work fails. For example, a teacher in danger of burnout might do well to invest time in family, hobbies, or other self-expressions. Others argue that some emotionally stressful jobs lead to burnout no matter how they are approached, and active efforts to overcome the stress before burnout occurs are important. The stress management techniques discussed in the next section may be lifesavers for people in such jobs.

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