Introduction to Psychological Science: Integrating Behavioral, Neuroscience and Evolutionary Perspectives - William J. Ray 2021

Stress and Health

LEARNING OBJECTIVES

✵ 11.1 Define stress and the ways people experience and respond to stress.

✵ 11.2 Discuss the early approaches to the study of stress.

✵ 11.3 Describe the autonomic nervous system (ANS).

✵ 11.4 Discuss the research that suggests that social relationships provide a protective mechanism in improving health and managing stress.

✵ 11.5 Explain the role of behavioral and emotional processes in the expectation of health outcomes.

Imagine you work in a large corporation. Everything seems to be going fine and then you hear that a number of people in your organization are losing their jobs. All of a sudden, your boss calls you into her office. How do you react? If you are like most people, you probably feel apprehensive. As you walk into her office, you may notice your heart beating a little faster and subjectively feeling anxious. Your boss then says sit down. As you wait for the worst, she says that she appreciates your hard work and would like to take you to lunch to hear more of your ideas. Although you clearly feel relieved, your body still continues to have an anxious feeling.

What Is Stress?

This chapter focuses on stress and health. As you can see in the scenario just presented, psychological factors play a critical role in how we experience stress. We can experience stress both from real situations and from our expectations of what might happen. Even after the event has passed, our body can continue to display characteristics of stress. Further, stress plays an important role in determining our health (O’Connor, Thayer, & Vedhara, 2021). How our body works in reaction to stress is an important aspect of this chapter.

Think about this. If you were to discover a wild animal in your path, as might have happened to our ancestors, what would you do? Your first instinct would be to leave the situation. In order to leave, you would need the ability to supply your body with the energy needed to move your legs as fast as possible, which includes your heart beating faster and your lungs obtaining more oxygen. Indeed, as you will see in this chapter, our body has such a system for dealing with threat. It is generally referred to as the stress response. It is also referred to as the fight or flight response.

Animals know who their predators are. They know when to run. As humans, we are different in that we don’t have predators who view us as their food. Of course, there are a number of ways that we humans can get into trouble. Unlike other animals, humans have no single predator. However, we do assess whether there is danger.

Stress responses have developed over our evolutionary history. The evolutionary logic of survival is one of the easiest to comprehend. If an organism is not able to successfully respond to threat, it can be hurt or killed. If it is killed, its genes can no longer be passed on. If it is hurt, this may make it a less appealing mate or less able to seek mates. Thus, it is expected that organisms will have evolved sophisticated mechanisms that benefit survival.

Over evolutionary time, organisms, including humans, have developed processes that protect them in dangerous situations. Animals never know when they could be attacked and eaten. This is the world of nature. However, as humans, we live more in culture than in nature and the chance of us seeing a bear is not a common experience. What we experience as stressful situations may not be life-threatening at all. For many people, flying on an airplane or giving a speech are stressful tasks.

Scientifically, stress is a difficult concept to define. The term is used in everyday language and in scientific research in a number of different ways. Stress is commonly defined as a response that is brought on by any situation that threatens a person’s ability to cope. Scientists speak of the stress response as a response to a critical situation that allows an organism to avoid danger or reduce other types of threat.

Stress is actually a complicated process that takes place on a number of levels. The cognitive level, that is, what we tell ourselves, is an important level. Physiologically, our body reacts without consciousness awareness. For example, some people show a higher blood pressure reading just by going to see a doctor. The white coat syndrome is so well known to medical professionals that they commonly take a second blood pressure measurement at the end of the examination. This second measurement typically shows a lower blood pressure reading.

Our bodies have a number of responses related to stress. For example, all individuals show a startle response when hearing an unexpected loud noise. Babies bring their arms and legs toward their chest. Adults typically blink their eyes and show flinching in their muscles. Some people also show unlearned reactions to looking down from a high place. Charles Darwin spoke of visiting the zoo in London and watching the snakes behind glass. He couldn’t help himself from jumping back when a snake attacked his image even though he was protected by the glass.

Culturally and socially, we may fear doing something at odds with our group and looking foolish to others. As seen previously, epigenetic changes also take place in reaction to stress. As you will see throughout this chapter, the different levels discussed in the first chapter of the book play an important role in stress. These different levels include cultural, social, individual, cognitive/emotional, physiological, brain, and genetic. As you will see, each of these levels are directly related to our responses to stress. For example, what we tell ourselves on a cultural, social, or individual level helps to identify situations in which we experience stress. Our experiences of stress involve our cognitive/emotional systems, which are determined in terms of physiological, brain, and genetic responses.

As humans, we share stress responses to similar situations. However, different individuals may respond to the same situation in very different ways. What we tell ourselves plays an important role. We as humans can talk to ourselves and characterize our world in positive and negative ways. This makes our emotional expectations and reactions an important aspect of what we consider stressful.

What if we just think there is a danger? This is part of the other side to the story. This is our ability to create our view of threat. As shown in the scenario of meeting with your boss, humans can anticipate that there is danger before actually knowing that there is a threat. Such threats can be losing a job, getting a disease, doing badly on a test, or having an accident. Unlike actually experiencing a dangerous situation, our anticipations can be totally wrong; however, our body may still show the stress response. Further, what is experienced as stressful may be different to different people.

Which of the following would be stressful to you?

✵ Being caught in traffic

✵ Being late for a meeting

✵ Seeing a bear

✵ Having two tests on the same day

✵ Seeing a physician

✵ Living with a roommate or partner you don’t get along with

As you think about each of these potentially stressful events, you realize they are very different. Seeing a bear in the wild could actually place you in danger. However, being late for a meeting is stressful for how you imagine others will think of you, but it is rarely a life-or-death situation. Seeing a doctor creates stress for some people since the possibility exists that the physician may discover that they may have a serious disorder. Being caught in traffic may evoke stress differently for each person. One person might find the loss of control difficult to experience, whereas another might feel she cannot accomplish what she set out to do that day.

Historical Approaches to the Study of Stress

In the early 1900s, the French physiologist Claude Bernard (1927) realized that the brain had circuits that were specialized for monitoring and controlling internal events, which he referred to as the internal milieu. These internal states included physiological processes such as thirst, temperature, and metabolism. This idea of an internal monitoring of bodily states underlies the development of the concept of homeostasis as described previously.

In 1915, Walter Cannon at Harvard developed the concept of homeostasis to reflect the manner in which a physiological system tended to center on a set point. Homeostasis is the process in which the body keeps itself in balance. Like a thermostat, if you become too hot, your body sweats to reduce heat by processes such as sweating and if you become cold, your metabolism is increased. In this view, the body’s reaction to stress was largely a passive and mechanical one. Stress for Cannon reflected the situation in which these systems deviated away from this set point. Thus, the concept of stress points to events that move your physiology out of balance. Cannon referred to homeostasis as the wisdom of the body that was controlled by the autonomic nervous system (ANS), which will be described later in this chapter (Cannon, 1932).

Another major figure in the history of stress research was the Hungarian endocrinolo-gist Hans Selye who worked at the University of Montreal. His work in the 1930s helped to set up the connection between stress and the development of diseases. It was Selye that borrowed the term “stress” from physics. In physics, stress refers to the strain placed on a physical material. Selye used the term as a way of organizing physiological responses to a variety of challenges including heat, cold, pain, noise, hard work, and so forth. In general, in response to different stressors, Selye’s laboratory animals showed peptic ulcers, enlarged adrenal glands, and negative immune system changes. One of Selye’s early findings was that the body reacts similarly to a variety of different stressors. Selye called this response the General Adaptation Syndrome (GAS).

The GAS involved three stages. The first was the alarm stage. The alarm stage was an initial reaction to the stress, which involved an increase in adrenal activity in terms of producing stress hormones and sympathetic nervous system reactions such as increased heart rate. The second stage was the resistance stage. This stage represents an adjustment to the stress, which includes the availability of additional energy resources and mechanisms for fighting infection and tissue damage. The third stage was the exhaustion stage in which bodily resources are depleted.

One paradox that Selye (1956) recognized was that the physiological stress responses that protect and restore the body can also damage it if allowed to continue over time (Selye, 1956). However, Selye also reported that repeated exposure to a particular stress situation could also increase the organism’s ability to withstand that same stress in greater amounts.

More recently, Bruce McEwen has begun to suggest a more flexible set of processes that involve the brain in the regulation of the body’s reaction to stress (McEwen, 2013; McEwen et al., 2015). McEwen begins by suggesting that part of the problem in understanding stress is the ambiguous meaning of the term stress. He suggests that the term stress be replaced with the term allostasis. Allostasis refers to the body’s ability to achieve stability through change. His view emphasizes the brain as the means of stability, which can be accomplished in a number of different ways. That is, there is not just one single response to stress according to McEwen.

Allostatic systems are designed to adapt to change. Change traditionally related to stress for humans takes on a broad range of possibilities including dangerous situations, crowded and unpleasant environments, infection, and performing in front of others. Some researchers even suggest that stress may be greater for humans than other animals since we are also able to use our cognitive abilities to increase the experience of stress through imagination.

The overall stress response involves two tasks for the body. The first is to turn on the allostatic response that initiates a complex adaptive pathway. Once the danger has passed, the second task needs to be initiated—turning off these responses. Research suggests that prolonged exposure to stress may not allow these two mechanisms to function correctly and in turn leads to a variety of physiological problems. This cumulative wear and tear on the body by responding to stressful conditions is called allostatic load.

Allostatic load has been discussed by McEwen in terms of four particular situations (McEwen, 1998).

1. The first situation reflects the fact that allostatic load can be increased by frequent exposure to stressors. These stressors can be both physical and psychological in nature. A variety of psychological studies have shown an association between worry, daily hassles, and negative health outcomes. One of the most studied areas is cardiovascular risk factors with stress showing a strong association with heart attacks and the development of atherosclerosis.

2. The second condition for the increase in allostatic load is where an individual does not adapt or habituate to the repeated occurrence of a particular stressor. For example, some people continue to show larger physiological responses to everyday situations like driving a long distance or taking an airline flight even though the data suggest there is limited risk in these situations. Asking individuals to talk before a group also induces stress-like responses in many individuals.

3. The third situation reflects the fact that not all individuals respond the same to changing situations. Some individuals show a slower return to a non-challenge physiological condition once the initial threat is removed. These individuals appear to be more at risk for developing health-related conditions. Some researchers suggest that high blood pressure is associated with a normal stress response not being turned off.

4. The fourth and final condition discussed by McEwen reflects the situation in which a non-response to stress produces an overreaction in another system. That is, if one system does not respond adequately to stress then activation of another system would be required to provide the necessary counter-regulation and return the system to homeostasis.

Overall, McEwen emphasized the important question of individual differences and the variety of ways in which perceived stress can influence future health. His graphic depiction of the allostatic system is seen in Figure 11-1. Following McEwen, others have also emphasized the role of the brain in making predictions about what physiological responses are needed to ensure evolutionary fitness (Schulkin & Sterling, 2019). Research has also shown that individuals who consume a high intake of fruits, vegetables, whole grains, fish, and poultry, and who engage in physical activities have lower allostatic load in comparison to those who do not (Suvarna, Suvarna, Phillips, Juster, McDermott, & Sarnyai, 2020). This reduction in allostatic load is associated with a reduction in chronic disease.

Figure 11-1 The brain interprets experience and determines what is threatening and therefore stressful.

CONCEPT CHECK

1. In what ways are the following seven levels directly related to our responses to stress: cultural, social, individual, cognitive/emotional, physiological, brain, and genetic?

2. Why is stress a difficult concept to define scientifically?

3. How did each of the following researchers define the term stress and our responses to it: Claude Bernard, Walter Cannon, Hans Selye, and Bruce McEwen?

4. Describe the three stages of Selye’s General Adaptation Syndrome (GAS).

5. What four particular situations or conditions does McEwen present in characterizing his concept of allostatic load?

Autonomic Nervous System (ANS)

We look over at the table and reach for a glass of something to drink. We put the glass back and pick up a book. These actions are voluntary, and we experience ourselves making them. Our brain sends signals through the spinal cord to the muscles involved.

Our brain also sends signals through what we experience as an involuntary system. We experience our body sweating as if someone else had made it happen. Our mouth becomes dry as we are about to give an important talk. We experience sexual arousal in a different way than reaching for a book. Sweating, dry mouth, and sexual arousal are all actions of the autonomic nervous system (ANS). There is an evolutionary logic to the ANS. In a time of danger such as seeing a bear, you want to be able efficiently to do what would protect you such as run. You would need increased blood flow and thus energy to help your legs run. You would also want to shut down any process such as digestion that could interfere with your running. These responses to danger and stress are controlled by the ANS.

The autonomic nervous system (ANS) consists of the neural circuitry that controls the body’s physiology (Wehrwein, Orer, & Barman, 2016)). This physiology involves organs such as the heart, gastrointestinal, genital, and lung systems (see Figure 11-2). Along with the endocrine system, the ANS manages continuous changes in blood chemistry, respiration, circulation, digestion, reproductive status, and immune responses. Two branches of the ANS are the sympathetic nervous system and the parasympathetic nervous system.

Figure 11-2 Sympathetic and parasympathetic branches of the ANS.

The sympathetic division of the ANS is involved in intense activity, seen in the fight-or-flight response. It is the purpose of the sympathetic nervous system to increase arousal and allow for a behavioral response. If we think there is danger or an emergency, it is the sympathetic branch of the ANS that is activated. Cannon (1929) suggested this happened in a diffuse, nonspecific manner. For example, if you are surprised by a bear as you walk in the woods, you run. Running requires blood, oxygen, and glucose to go to the periphery of your body to fuel your leg muscles.

As shown in Figure 11-2, this situation quickly turns on the sympathetic division of the ANS to ensure the ability to quickly leave the situation. Your heart speeds up and your blood vessels in the skeletal muscles enlarge. This ensures your muscles receive the energy they need to function properly. Since digestion is not needed and would use valuable blood supply, those processes are inhibited. However, glucose from the liver is increased. Also, as can be noted from Figure 11-2, the sympathetic division is activated at the middle (thoracic and lumbar) divisions of the spinal cord.

If you’re able to escape the bear, what happens next? You need to calm down and rest! The system involved in the rest and digest response is the parasympathetic division of the ANS. It is the function of the parasympathetic division to return the system to homeostasis and to store energy. As can be seen in Figure 11-2, the parasympathetic system performs operations opposite to the sympathetic division. It shuts off what the sympathetic division turns on and turns on those systems involved in digestion and energy storing. As noted in Figure 11-2, the parasympathetic division is activated through the top (cervical) and bottom (sacral) parts of the spinal cord. Although it was historically thought that the sympathetic and parasympathetic divisions worked in opposing ways, this is not always the case. We now know that they both can increase or decrease together (Berntson, Cacioppo, & Quigley, 1991; Christensen, Wild, Kenzie, Wakeland, Budding, & Lillas, 2020).

Initially, many of the systems described in this chapter, such as the autonomic nervous system, the endocrine system, and the immune system were considered to function independently. However, we now know that not only do internal pathways exist allowing for communication among the systems, but also external psychological and cultural influences can play a role. There is also recent research to suggest that a hormone released by our skeletal structure may also play a role in the stress response (Berger et al., 2019). Overall, our response to stress involves a number of integrated systems including our brain’s ability to predict what is needed.

Physiology of Stress

One critical mechanism involved in response to stress includes the autonomic nervous system, which we just discussed, and a network of hypothalamic, pituitary, and adrenal responses shown in Figure 11-3 as well as the cardiovascular system, metabolism, and the immune system.

Figure 11-3 Basic mechanisms involved in response to stress.

The brain has two major pathways in which it influences peripheral physiology. These pathways are distinct but interrelated (see Gunnar & Quevedo, 2007 for an overview). The first is more fast acting and is referred to as SAM (sympathetic adrenal medullary system). The second pathway is slower and referred to as the HPA (hypothalamic pituitary adrenal) axis.

The SAM (sympathetic adrenal medullary) system involves the sympathetic division of the autonomic nervous system. As shown in Figure 11-4, stress can be seen to influence the body in two different ways. First, the adrenal medulla is activated, and adrenaline (epinephrine) is released. Second, nerves of the sympathetic nervous system stimulate organs of the body such as the heart and lungs to increase their output. The basic consequence of this action is to prepare the body for action.

Figure 11-4 The SAM pathway.

In humans, the HPA (hypothalamic pituitary adrenal) pathway (Figure 11-5) involves the hypothalamus, which releases cortisol into the bloodstream, which goes to the pituitary gland in the brain. Cortisol is a major stress hormone, which increases glucose in your blood and thus increases energy both in your body and brain. Release of cortisol causes the pituitary to release hormones that influence other hormones, which in turn influence peripheral organs such as the adrenals and cells in the immune system. This system helps to convert stored fats and carbohydrates into energy sources that can be used immediately. Over our human history, survival processes that activated this system would have involved conflict and fights, so it was important that the immune system also be activated to protect the organism from wounds.

Figure 11-5 The HPA pathway.

The SAM and HPA systems have been studied as part of stress. The SAM stress response was initially described by Walter Cannon as a bodily response to danger. Although Cannon originally studied animals, since his time, research has shown the basic stress response also applies to humans.

Previously, you learned that the neuron can secrete a chemical, a neurotransmitter, which influences how the signal is passed to the next neuron it connects with. However, if the chemical is secreted into your bloodstream and influences different processes in your body, that chemical is referred to as a hormone. Thus, depending on the situation, norepinephrine, for example, can function as either a neurotransmitter or a hormone.

What happens when you are faced with a potential threat? According to Cannon, your body prepares you either to fight or to leave the scene. How does it do that? Since Cannon’s time, we have come to see that the stress response is accomplished by a variety of interacting systems, which include the amygdala and other cortical systems, resulting in the hypothalamus activating the sympathetic nervous system and the HPA axis. The hypothalamus is able to release hormones that increase certain processes as well as inhibit others.

Basically, the hypothalamus in your brain produces a substance referred to as CRF (corticotropin-releasing factor, also called CRH (corticotropin-releasing hormone)), which in turn produces ACTH (adrenocorticotropic hormone) in the pituitary. It is the pituitary that is able to influence glands in your body. Thus, ACTH in your blood in turn results in the adrenal glands producing cortisol. Research studies will often take a measure of cortisol to reflect the stressfulness of the situation. Cortisol can be measured by swabbing a Q-tip in your mouth.

During stress, the sympathetic nervous system releases norepinephrine and epinephrine (noradrenaline and adrenaline) into your blood stream. During this activation, your heart rate is increased, sending blood to your legs and arms so you can be ready to fight or flee. Other sympathetic responses include the dilation of the pupils, which allow you to see better in shadows and darkness, increased breathing rate, and the reduction of blood flow into organs not involved in action.

Does “Fight and Flight” Apply Equally to Males and Females?

After examining a variety of studies, Shelley Taylor and her colleagues (Taylor et al., 2000) suggest that the fight or flight response better describes a human male’s response to stress and not a female’s. For females, they suggest a better descriptor is the tend and befriend response. What do they mean by this? They make three major points.

1. They suggest that over evolutionary time, females have evolved behaviors that maximize the survival of both themselves and their offspring.

2. When stressed, females respond by nurturing offspring as well as displaying behaviors that protect them from harm. These tending behaviors have also been shown to reduce the presence of stress hormones in the infants.

3. Like fight or flight, these behaviors are associated with particular neuroendocrine responses, although different hormones are involved. One of these hormones is oxytocin.

Oxytocin is rapidly released in response to stress in females. When released, oxytocin increases affiliative behaviors. Associated with this is an increase in feeling relaxed and calm. Females under stress seek contact with their social group, which is also protective in survival terms. In many ways, this is the opposite response seen with the fight or flight response. The tend and befriend response is seen across females of a variety of species and not just human females.

These responses make up the tending response. The tending response activated by stress is seen as part of the larger attachment process that was discussed previously. The befriending response involves a large social group.

What is intriguing is that the basic neuroendocrine responses to stress appear to be similar in both males and females (Kudielka & Kirschbaum, 2005). It is an initial sympathetic response as described previously. What is different is that these hormones affect males and females differently. Human males show the sympathetic response of activation and increased arousal, which can lead to aggression—the fight part of fight or flight. The male brain appears to be organized to give aggressive responses in the presence of such substances as testosterone that are less present in the female brain.

What is present in the female brain is the hormone oxytocin, which is released in larger amounts in females compared to males. Oxytocin has been found in a variety of animal studies to reduce anxiety and calm the organism. According to Shelly Taylor and her colleagues, oxytocin leads females to quiet and calm down offspring in response to stress. Thus, whereas males are seen to produce more sympathetic-like responses to stress, females show more parasympathetic-like responses. Oxytocin is considered to lie at the basis of these responses for females—the tend and befriend response.

Additional support for the presence of gender differences in response to stress has come from the work of Repetti (1989). She examined the behaviors of fathers and mothers following a stressful workday. Whereas fathers tended to isolate themselves at home following stress, mothers tended to be more nurturing and caring toward their children. Further, similar differences also are found in the larger social networks. That is, when stressed, females tend to seek out other women for comfort and support. Compared to females, males seek support from same-sex friends less often. A variety of anthropological studies suggest that males and females form groups for different purposes. Male groups tend to be larger and directed at well-defined tasks such as defense. Female groups tend to be smaller and carry with them social and emotional connections to a greater degree.

Why did researchers initially not see differences in male and female responses to stress? The answer is simple. During most of the 20th century, females were not studied in this research. Even the animal studies typically used males. Once females were studied more intensely, then these differences were observed for the first time. If you think about it, you can see that these stress-response differences are consistent with mating differences and investment in the care of offspring. That is, given that females typically have a greater role in caring for offspring, then her response to stress should not jeopardize herself or her offspring as might be the case with fleeing or fighting.

Immune System

Our immune system is there to protect us from various germs, also called pathogens, that make us sick. Our immune system also produces inflammation such as that you may experience with an insect bite. As you will see, at birth our immune system already knows how to recognize and destroy some pathogens. However, our immune system can also learn to recognize new pathogens through experience. Day care and nursery school are often places children trade their sicknesses with one another. Basically, the immune system learns to recognize the presence of specific pathogens. Today, measles, chickenpox, mumps, diphtheria, whooping cough, yellow fever, and polio can be prevented through vaccines that activate the immune system. However, novel pathogens that are unknown to our immune system have caused real problems throughout human history. The COVID-19 pandemic seen in 2020 is the most recent example.

What is less well known is that stressful events activate the same immune and brain circuits as do infections (Watkins & Maier, 2002). Why is this so? Maier and Watkins suggest that the immune system first evolved to be sensitive to pathogens such as those associated with disease—for example, the common cold. It then began to use the same systems to respond to stress. In evolutionary time, the immune system is thought to have evolved before such responses as fight or flight since all organisms have mechanisms for dealing with pathogens.

Psychological factors can also affect the immune system. At one time, the immune system was viewed as a separate system that functioned independently. However, since the 1970s a variety of studies have demonstrated that the immune system is influenced by the brain and vice versa. In the 1980s, Robert Ader was able to show that the immune system could be changed through learning (see Ader, 2003 for an overview). In particular, they showed that animals could learn to associate specific experiences with changes in their immune system.

It has also been shown that stress can influence the immune system such that the organism is more likely to become ill following stress. Some early research studied medical students taking their exams, which they experienced as stressful. Yes, even taking an exam can influence your immune system. Thus, the immune system comes into play in terms of both stress and specific pathogens.

Understanding how an event was perceived could influence your immune system and how this involved brain processes created the new field of psychoneuroimmunology. One meta-analysis of more than 300 studies suggests that stress in the form of loss or trauma will suppress the immune system (Kiecolt-Glaser, McGuire, Robles, & Glaser, 2002). This review shows that negative emotions can change immune responses and delay healing. Some of the psychological factors that can influence the immune system include loneliness, poor social support, negative mood, disruption of marital relationships, bereavement, and natural disasters.

These same negative factors can also lead to psychological disorders such as anxiety and depression. It is suggested that inflammation produced by the immune system is how this comes about (Bullmore, 2019; Dooley et al., 2018). In particular, it is suggested that environmental and social stress produces an elevation in inflammation (Slavich & Irwin, 2014). This inflammation may in turn be related to the development of depression in both young adults and old age (Bell et al., 2017). One longitudinal study measured inflammation markers at age 9 and again at age 18 (Khandaker, Pearson, Zammit, Lewis, & Jones, 2014). Those participants who showed higher levels of inflammation markers at age 9 were more likely to experience depression at age 18 compared with those with low levels of the markers.

If negative emotions can suppress the immune system, is the opposite also true? The answer is yes. Positive affect or the experience of pleasurable emotions is associated with better health outcomes (Pressman, Jenkins, & Moskowitz, 2019). Factors such as close friendships, which reduce negative emotions, also enhance immune-system functioning. It has also been shown that positive affect can reduce the effects of stress and reduce the chance of developing anxiety and depression (Sewart et al., 2019). Additionally, it has become apparent that not only does experience influence the immune system but that the immune system can influence the brain and thus behavior (Kipnis, 2018). Let’s now look at the nature of the immune system.

Overall, our body needs a way to protect itself from toxins from the outside. Over evolutionary time, organisms developed various types of skin to initially accomplish this goal. Basic reflexes such as sneezing, coughing, and crying are additional mechanisms for removing pathogens before they can enter the body. However, if a pathogen does get inside our body, the immune system is called into action. It is the task of the immune system to recognize foreign agents in the body and destroy them. There are a number of layers of immune function.

The defense mechanisms of the immune system appear to be some of the earliest to have evolved. One important task of the immune system is to determine what is foreign and what cells are part of the self. These foreign substances include bacteria, viruses, and parasites, which enter our system and are detected by the immune system. Antibodies that are produced by our immune system can detect literally millions of different foreign substances and engage in a process that—in the best case—leads to their destruction. Our immune system has evolved to recognize a variety of pathogens. It is also capable of learning the characteristics of new pathogens and attacking them upon later exposure. This, of course, is the basic mechanism through which immunizations work.

There are two major types of immunity that protect the organism (see Brodin & Davis, 2017; Rouse & Sehrawat, 2010 for overviews).

1. The first system is general. It involves those processes of the immune system that are present at birth, and it responds to a variety of pathogens including bacteria and other toxic organisms. It tends to be fast-acting, nonspecific, and usually of short duration.

2. The second type of immunity develops after birth. This type of immunity is involved in recognizing specific pathogens, such as bacteria, viruses, or toxins, after initial contact. This system is more long-lasting and is able to contain a memory of a specific pathogen. This system is also the basis of immunizations for preventing specific diseases.

Overall, the two immune processes—both innate prevention at birth and learned recognition after birth—are what we usually focus on in discussions of the immune system in fighting infections. However, it is even broader than that. The immune system is designed to attack whatever is not you. That is why you have allergies. Allergies are simply your immune system attacking what it considers a pathogen. It is also why so much care must be taken in organ transplants. The immune system realizes that the transplanted organ is not yours and may even attack it. Although we experience the effects of the immune system, especially with allergies, most of what it does takes place outside of awareness. Let’s look at the immune system itself (see Parkin & Cohen, 2001 for an overview).

There are a variety of types of immune cells. In general, immune cells originate in the bone marrow. Some of these cells migrate to the thymus and develop into T cells. T cells circulate through the blood and lymph systems as well as exist in the lymph nodes. There are also other types of cells such as B cells that produce antibodies. Both B and T cells require prior exposure to the pathogen to produce an immune response. Other natural killer (NK) cells do not require prior exposure and form a first line of defense against pathogens. Additionally, the spleen contains white blood cells created in bone marrow that fight infections and disease.

In addition to attacking pathogens, immune-system responses are also associated with the experience of feeling ill. From an evolutionary perspective, feeling ill would be protective as it would result in withdrawal from dangerous situations as well as allow for rest. Also, from an evolutionary perspective, interacting with our environment can actually educate your immune system, as described in the box: Myths and Misconceptions: Keep Your House Clean—Dirt Is Bad for You.

Myths and Misconceptions: Keep Your House Clean—Dirt Is Bad for You

Although television and media commercials suggest that we should keep our houses immaculately clean and our children out of the dirt, current research suggests that this may be actually hurting our health.

One study compared children from two Christian religious rural groups—the Amish and the Hutterites (Stein et al., 2016). Both of these groups eschew much of modern technology and make their living by farming. The Amish typically have houses without electricity and use horses and buggies instead of trucks and cars. Amish farming uses farm animals to pull plows and move crops. Likewise, their tools are those seen at the end of the 1800s. The Hutterites, on the other hand, live on highly industrialized communal farms with modern equipment.

The question asked was did these different lifestyles influence their health. Previous researchers found that the prevalence of asthma in Amish children was 5.2%, whereas it was 21.3% in the Hutterite children. Further, the sensitivity to allergies was also lower (7.2%) in the Amish as compared to the Hutterite children (33.3%). The current study found no asthma in the Amish children and 20% in the Hutterite children.

Why did this happen? The basic idea is that dirt and common allergens found in the Amish communities protected the children from later disorders. These allergens educated the child’s immune system to know that it did not need to react at a later time. The Hutterite children, on the other hand, had an immune system without this information and later encounters with allergens produced a stronger reaction. Of course, you might think that the Amish and Hutterites had a different genetic makeup and this produced the differences. However, both of these groups originally came from nearby areas in Europe and are genetically similar.

In order to test the hypothesis that it was the levels of natural substances that educate the immune system, the researcher first tested the levels of dust and animal substances that can cause allergic reactions in the households. These are referred to as endotoxin levels. Indeed, the endotoxin levels were much higher in the Amish homes as compared to the Hutterite homes.

To further test the idea that the dust and other substances found in the home were involved in the prevention of asthma, the researchers exposed young mice to these substances over time. The mice that were exposed to the dust from the Amish houses showed less of a response to asthma-producing agents than did control animals. The mice that were exposed to dust from Hutterite houses showed a larger asthma response. Other studies have also shown that mice exposed to microbes during early childhood show more protection from immune-system-related disorders such as inflammatory bowel disease and asthma (Olszak et al., 2012).

Thus, for their own good, we might want to give children a chance to play in the dirt and visit farms as they are growing up and their immune systems are developing.

Thought Question: If you were running a daycare for young children, how might you change your approach to planning activities for the children based on these findings? How would you explain your approach to the parents?

CONCEPT CHECK

1. What is the autonomic nervous system (ANS)? Describe the steps it goes through when you unexpectedly run into a bear in the woods. What steps does it go through when the bear runs away and you make it safely back to your car?

2. Describe how the SAM and HPA pathways work as part of the human stress response. What is the unique contribution of each pathway to that response?

3. Describe the three important characteristics of Shelley Taylor’s concept of tend and befriend, the female response to stress.

4. What is the same and what is different in the male (fight or flight) and female (tend and befriend) responses to stress on the physiological level?

5. What are three ways in which psychological factors, stress, and our immune system are interrelated?

6. Describe the two major types of immunity. What is the primary contribution of each type?

Social Support Research and Stress

Do you ever take a friend with you when you are about to do something that you imagine will be stressful? If the answer is yes, then you may be preventing or reducing the normal stress response. A variety of studies show that if a friend is present, you experience less stress than when you perform the task alone (see Knox & Uvnäs-Moberg, 1998; Taylor & Stanton, 2007 for an overview). After school shootings, individuals comfort one another. Other people find animals supportive and find them to bring comfort. Various studies have shown that following disasters and other negative events such as terrorist attacks, humans turn to others for comfort.

What this suggests to a number of researchers is that we should view social relationships and bonds as a protective mechanism. That is to say, whereas different organisms have a variety of protective mechanisms, including camouflage, thick skin, sharp teeth, and quick reflexes, in humans, social relationships serve a similar function (Taylor et al., 2006). The opposite has also been shown to be the case. Social isolation is shown to be unhealthy and associated with a risk for disease and early mortality.

One of the first forms of the social bond that humans experience is attachment. Attachment is the relationship infants have with their caregivers. Although you learned about attachment in the chapter on development, attachment is usually not discussed in terms of its health benefits. However, a variety of studies suggest that early attachment relationships help to influence later reactions to stress (Taylor et al., 2006). For example, rat pups who received positive maternal care showed less negative hormonal response to stress. These animals also showed more open field exploration, suggesting less anxiety.

In another study, monkeys were raised in one of three environments (Rosenblum & Andrews, 1994). In the first environment, food was readily available, and the mothers were attentive to their young. In the second environment, food was less readily available, but the mothers were still attentive to their offspring. In the third environment, food was sometimes available and sometimes not. This condition resulted in the mothers being harsher and inconsistent in their mothering. The offspring in this third condition displayed more clinging behaviors to their mothers and lower levels of exploration and social play.

As adults, these monkeys displayed more extreme HPA axis responses to stress. They also appeared more fearful and lacked the normal social responses. With humans, similar responses are seen in response to difficult rearing environments. For example, in a study of 13,494 adults, a relationship was found between exposure to abuse and household dysfunction and later adult negative health outcomes (Felitti et al., 1998).

The evolutionary link that connected social challenges with the stress system for life-and-death situations is less well understood. One would assume that, as with many other evolutionary processes, nature used systems already available. Flinn (2007) reviews the idea that the adaptive value of the social stress response begins in childhood. A variety of studies across a variety of species has shown that early exposure to stress will modify how the stress response is expressed in later life and how early stress influences the brain (Murthy & Gould, 2020). It appears that children who experience trauma in the form of abuse, death of a parent, or divorce, show larger stress responses to social stress later in life. It is the not the case, however, that early physical stress such as experiencing hurricanes or political upheaval in one’s country results in a differential stress response.

A number of studies in animals, particularly rats, has shown that early life stress can make a number of changes in the stress response throughout the animal’s life (Maras & Baram, 2012). In particular, early stress increases CRF expression throughout life in response to stress. Early stress also changes the nature of neuronal connections. Pyramidal cells of adult rats that have experienced chronic early life stress do not grow as well compared to those without stress. Those with early life stress have less well-developed dendrites. Since stress influences the hippocampus, this can in turn influence later life learning and memory. Research also shows less synaptic density in humans in relation to long-term stress (Holmes et. al., 2019).

Childhood stress also results in brain differences in humans (Teicher, Anderson, Ohashi, & Polcari, 2014). When these authors examined 142 men and women who had experienced childhood abuse in comparison to 123 men and women who had not, they found differences in those areas of the brain related to emotional regulation and perception as well as areas related to self-and other-awareness. These areas were the anterior cingulate, the insula, and the precuneus. The anterior cingulate plays an important role in attention and the regulation of emotions. The insula is involved in experiences of the self and the importance of those experiences as reflected in the salience network. The precuneus is involved in the default network and internal thoughts and images. As you will see at the end of this chapter, these areas are also related to stress reduction through meditation. Figure 11-6 shows that brain connections differ between those who were maltreated in childhood and those who were not.

Figure 11-6 Brain connections in those who were maltreated as children and those who were not.

Social Shaping

Based on the studies examining social relationships and health, Taylor and Gonzaga (2006) developed a social shaping hypothesis. Overall, this hypothesis suggests that early social relationships can shape the manner in which a person’s biological, social, and behavioral processes respond to a variety of situations including stressful ones. For these researchers, social shaping has three functions.

1. Early relationships can calibrate how those systems involved in stress responses will develop.

2. Social relationships help to regulate the stress response in terms of day-to-day experiences. Social relationships tend to buffer stress responses, whereas the lack of social relationships tends to exaggerate the responses.

3. Social relationships can serve as a source of information as to the nature of the present environment. The information can be presented directly or indirectly.

The research suggests that people with social support live longer. On the other hand, those who are isolated display more detrimental health problems. For example, there is a variety of studies that show a strong relationship between social isolation and subsequent cardiovascular morbidity. Overall, social support reduces cardiovascular reactivity to acute stress, and lack of social support is associated with increased resting levels of sympathetic activation. Thus, lack of social support may itself be a stressor.

Individual Differences

Not everyone responds to the same stressor in the same way. Some individuals like to eat foods, especially sweets, after stress. Some people have comfort foods that they eat during chronic stress. It turns out that for some individuals comfort food does indeed reduce stress (Dallman et al., 2003). To eat during or after stress is referred to as stress eating. However, some individuals show the opposite reaction to stress and do not crave foods. The reason for this is both psychological and related in a complex way to the amount and types of hormones you secrete. In a group of 131 medical students (55% were female), weight gain during an exam period was about 5 pounds for the stress-eating group. There was also an increase in cortisol and insulin secreted during the night (Epel, Jimenez, Brownell, Stroud, Stoney, & Niaura, 2004).

Individual differences in stress are also shown in our cardiovascular system. More than 50 years ago, two cardiologists, Meyer Friedman and Ray Rosenman, were trying to study factors such as diet related to heart disease. The story goes that the wives of the men with heart disease helped these cardiologists understand it was stress that was influencing their husbands. Specifically, these cardiologists began to understand that how these men approached the world was a factor in their disease. This pattern of behavior became known as the Type A pattern of behavior. Individuals with Type A showed four major characteristics:

1. Competitiveness—Type A individuals take most tasks, such as driving in traffic, as a form of competition. This need for competition often takes the joy out of doing the task.

2. Time urgency—Type A individuals are impatient and constantly performing tasks as if they are fighting the clock. This may lead to trying to perform a number of tasks at the same time.

3. Anger and hostility—Type A individuals often react to others in an angry and hostile manner although they may not show the anger.

4. Forced speech—Type A individuals may talk over others and display a pressured style of speech.

Individuals who show the opposite pattern with low levels of competitiveness, time urgency, anger, and forced speech are referred to as Type B individuals. Consistent research has shown that those with a Type A pattern of behavior are at greater risk for coronary heart disease (CHD). This can result in symptoms of angina, which is experienced as chest pains. CHD is also associated with heart attacks. Overall, it is suggested that Type A individuals are twice as likely to develop CHD and die of heart disease than non-Type A individuals. Later research suggests that the critical factor that connects Type A behavior to disease is hostility. Hostility may also influence other factors such as making it difficult for the person to experience social support or respond to stress in a productive manner.

Uncontrollable Stress

Another critical factor in how we experience a situation is whether we feel that we are in control or not. Over the past 50 years, a variety of studies have shown that individuals who experience high demands in their jobs but have little control over how and when they perform their work have been shown to display more symptoms of a variety of disorders including heart disease. Those individuals who felt that they had control even though they may have had demanding jobs displayed fewer disorders.

Jay Weiss examined the results of uncontrollable stress (see Weiss, 1972). Uncontrollable stress is a negative experience that the organism cannot influence or control. In experimental animals, such procedures as shock will produce stress. To examine the effects of control, researchers used a procedure referred to as yoked-control. The control animal is in the same experimental procedure but does not receive any shocks. Another animal can perform a task to turn off the shock once it begins. The other rat receives the same shocks but does not have the ability to turn it off. What became apparent in this research was that uncontrollability produced both health problems (for example, gastric ulcers) and depressive symptoms.

What was intriguing was that the depressive symptoms in animals were very similar to clinical definitions of human depression. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM), which is used by psychologists and psychiatrists in the United States and other parts of the world, depression includes such symptoms as loss of appetite, psychomotor retardation, fatigue, disrupted motivation, sleep disturbances, and reduced capacity for attention. These were exactly the symptoms that Jay Weiss and his colleagues found in the organisms they studied (Weiss et al., 1981). This has led some researchers to examine the role of stress in experiencing depression. An interesting Radiolab presentation by Robert Sapolsky describes our reactions to stress (https://www.wnycstudios.org/story/91580-stress).

CONCEPT CHECK

1. Describe three studies from this chapter that show how social relationships and bonds serve as a protective mechanism in terms of stress.

2. What brain changes have been observed in adults as a result of their exposure to early childhood stress?

3. Describe Taylor and Gonzaga’s social shaping hypothesis. What are its implications for both social support and social isolation?

4. Not everyone responds to stress in the same way. How is the fact of individual differences evidenced in the two examples given here: (1) eating and (2) our cardiovascular system?

5. What do Jay Weiss’s experiments with rats and other researchers’ studies with humans reveal about the role of individual control in how they experienced stress?

Trauma and PTSD

Psychological stress and trauma are experienced when something happens to us that we do not expect. Generally, these situations put us in a position where we have little control over what is happening to us. Besides the initial stress response, these types of experiences can lead to a particular long-term problem referred to as post-traumatic stress disorder (PTSD). PTSD can result both from experiencing trauma, such as sexual assault, serious injury, or a death-threatening situation as the victim, or from seeing others in these sorts of situations. PTSD can result from one traumatic event or a series of traumatic events, as would be seen by solders in combat.

Those who experience PTSD will have memories of the traumatic event break into their consciousness without warning. It is also the case that physical events associated with the traumatic event can bring forth a flashback or re-experiencing of the event. This re-experiencing can include bodily and emotional responses associated with stress. This leads some individuals to avoid situations that could remind them of the previous trauma.

PTSD can also lead individuals to having distorted ideas and emotions, including blaming themselves for the event. This is especially true in cases of sexual assault in which the person feels shame and sees herself or himself in negative terms. They may also be irritable and sensitive to others and their surroundings. It is common for those with PTSD to have sleep problems and intense dreams. Those with PTSD may also seek to self-medicate with alcohol or drugs. PTSD is a complicated disorder in that not everyone who experiences similar stressful conditions develops PTSD. Table 11-1 shows some of the stressors that can lead to PTSD.

Source: Vermetten and Lanius (2012, p. 293).

PTSD has been an important focus of the US Department of Veterans Affairs, since PTSD shows up in greater numbers in the military than in the general population. Part of this results from the nature of current military actions in wars in which small groups of soldiers go out from the base and cannot predict when there will be an attack. In this situation, there is not a traditional front line. Further, roadside bombs and suicide bombers present additional dangers. Thus, soldiers find their lives under constant threat.

Among Vietnam veterans, lifetime prevalence of PTSD is estimated to be 30.9% for men and 26.9% for women (https://www.ptsd.va.gov/index.asp). For Gulf War veterans, lifetime prevalence is lower and estimated to be about 10% to 12%. The Iraq War estimates are about 13.8%. Soldiers who were in recent war zones have not only experienced PTSD but also mild traumatic brain injuries (TBIs) usually in the form of concussions. Additionally, sexual assault was reported by 23% of the female veterans who use VA health care facilities.

One way to consider the physiological changes associated with trauma is to consider the networks involved on both an associative level and on a cortical level. On an associative level, it has been suggested that some associations become more potent or “hot” than others that remain “cold.” A hot association is one that, when we consider it, we react strongly and emotionally. If we were afraid of walking in a certain part of town, this would be a hot association when someone mentioned that possibility. A cold association is one we have little reaction to, such as remembering that a grocery store is on 3rd Avenue. The same set of facts can be either hot or cold depending on the experiences associated with it. It has been shown that repeated experiences of trauma will make it more difficult to integrate the experiences into less emotional, or cold, autobiographical memories. Figure 11-7 illustrates such a network in which being on a dark street results in a cognitive proposition such as “there is no way out” and the following emotional and physiological responses.

Figure 11-7 Elements of “hot” memory.

One goal of therapy is to help the individual move the hot trauma associations to a cold, or nonreactive, memory process. PTSD is frequently comorbid with other disorders such as depression, substance abuse, and anxiety disorders such as obsessive-compulsive disorder (OCD), panic disorder, agoraphobia, and social anxiety. For example, the National Vietnam Veterans Readjustment Study shows that 98% of individuals with combat-related PTSD have a comorbid lifetime mental disorder (Kulka et al., 1990). They also reported more physical health problems. This suggests that the treatment of PTSD requires more than a single strategy.

In terms of brain structures, animal models of stress and trauma have shown that exposure to severe and chronic stress can damage hippocampal formation. This is seen to be mediated by elevated corticosteroids, which are thought to damage cells, diminish neuronal regeneration, and reduce dendritic branching. This has resulted in a variety of human studies examining the hippocampus in individuals with PTSD.

In addition, an improved understanding of the cortical networks involved in emotional regulation, threat detection, and the acquisition and extinction of fear have pinpointed specific brain regions connected with PTSD (Shalev, Liberzon, & Marmar, 2017). These include the hippocampus, the amygdala, and medial prefrontal cortex (PFC). The hippocampus is important because of its role in the encoding of memories including emotional ones. The amygdala is involved in the assessment of threat and plays a role in fear conditioning. The medial PFC, including the anterior cingulate cortex (ACC), is involved in the inhibition of emotional information during task performance. The brain regions involved in PTSD are shown in Figure 11-8.

Figure 11-8 Cortical networks involved in the acquisition and extinction of fear.

In general, there is clear support that individuals with PTSD have smaller hippocampal volume than those without PTSD. In one meta-analysis, individuals with PTSD had, on average, a 6.9% smaller left hippocampus and a 6.6% smaller right hippocampus by volume. An intriguing idea is that stress limits the normal regeneration of new neurons in the hippocampus. ACC differences have also been noted in PTSD as well as reduced connectivity between the ACC and the amygdala.

The amygdala also can take in information that bypasses the frontal lobes (see Sapolsky, 2003 for an overview). This may be part of the experience of vivid flashbacks in PTSD. In turn, this hyper-responsiveness of the amygdala is related to an exaggerated fear response. This may result from a lack of inhibition from the frontal areas to the amygdala. This would also be associated with the inability to inhibit or extinguish fear-related stimuli.

CONCEPT CHECK

1. How is post-traumatic stress disorder (PTSD) different from a typical stress response?

2. What are some examples of events that can bring forth PTSD?

3. What are some common symptoms of PTSD?

4. How does PTSD play out on the memory and emotional levels?

5. Describe three changes seen in the brains of individuals with PTSD?

Health

We usually only think about health when we experience its opposite, that of a disease or a disorder. We also tend to look for biological reasons such as viruses or bacteria as the cause of the problem. We now know that psychological factors play a critical role in health and disease. What we choose to eat, how we exercise, and even how we think and feel are critical factors in our health. This has been a change over the past 100 years, which is found in the field of behavioral medicine and health psychology.

One part of this has been the study of resilience. Resilience research seeks to understand how some individuals are able to encounter severe psychological or physical adversity without showing traditional stress effects (Kalisch, Müller, & Tüscher, 2015). One key finding suggests that resilience is associated with the ability to reinterpret both internal and external events in a more positive manner. This is similar to some of the factors associated with mindfulness meditation.

Since the beginning of the 20th century, health statistics have shown a change in terms of both types of diseases encountered and the role of behavioral processes. The top three leading causes of death in 1900 were related to infectious diseases. With the advent of public water supplies and sewage treatment plants, the death rate percentages of these disorders were greatly reduced, as shown in the 1997 figure. Figure 11-9 shows the exact number of deaths by disorder from 2017—more than 100 years later. One important change is that current causes of death can have a behavioral component, such as the types of foods eaten or drugs used.

Figure 11-9 Cause of death in the United States for 2017. US population was approximately 325 million.

These behavioral factors can have both direct and indirect effects. Accidents and suicide have strong behavioral components. For example, not sleeping enough or using drugs and alcohol can lead to highway accidents. Other disorders have related behavioral components. Using tobacco can also lead to various cancers. Being overweight has a direct relationship with diabetes. Heart disease, which is the number one cause of death in the US currently, is associated with behavioral factors such as the foods one eats, exercise, smoking, and alcohol use. The top four major causes of death today result from a slow accumulation of damage that involves behavioral components.

During the 20th century, psychologists became health care professionals. This represents an understanding that treatment of most disorders involves a strong behavioral and emotional component. In fact, different individuals recover differently from the same disorder. This has led to both research and treatment studies involving psychological factors and health. As described in Chapter 1, the biopsychosocial model of health continues to be important. Overall, it became clear that culture, lifestyle, and physical components such as genetics needed to be considered to understand health and disease.

With the development of better public works systems and sanitation and medical treatments including vaccinations, life expectancy began to increase. The World Health Organization (WHO) has collected statistics regarding health and disease from around the world. Figure 11-10 shows a map of healthy life expectancy from around the world in 2016.

Figure 11-10 Healthy life expectancy at birth in 2016 for both sexes.

In 2016, healthy life expectancy was 63.1 years globally. However, many individuals end their lives with a disorder such as cancer or Alzheimer’s disease that leads to a disability. Life expectancy including those in both healthy and disabled states was 62 years worldwide in 2015. The United States had an overall life expectancy for 79.3 in 2015. It was 76.9 years for males and 81.6 years for females. By the way, the United States is 31st in the world in terms of life expectancy. Japan is number one with an overall life expectancy of 83.7 years. Compare this to 1889 in Germany when the first social security pension was established by Chancellor Otto von Bismarck. At that time, life expectancy was 45 years of age.

Applying Psychological Science: The Role of Expectation in Health Outcomes

Giving a drug to treat a disorder seems fairly straightforward. One might even think that psychological factors would not be involved. Take Parkinson’s disease, for example. Parkinson’s disease is a motor disorder that affects about 1% of the population more than age 60. People with the disorder may show tremors, particularly involving the hands, and a slowness of movement when walking. The disorder is associated with the loss of neurons that produce the neurotransmitter dopamine in one particular part of the brain, the substantia nigra. Treatment for the disorder is to give a medication that increases dopamine in the brain.

Researchers told 12 individuals with Parkinson’s disease that they were testing a new injectable drug that increased dopamine along with a lower priced drug of similar efficacy (Espay et al., 2015). The new drug cost $1,500, whereas the lower cost one was $100. Both drugs were actually a normal saline solution, which does not influence dopamine, that is, a placebo. Following administration of the drugs, the individuals with Parkinson’s disease were given motor tests and an fMRI task.

Both placebo drugs improved motor function, and the expensive placebo drug worked better than the cheap one! It not only improved motor function but also showed brain-imaging changes consistent with an increase in dopamine. These researchers suggest that an expensive medication increases the expectation of change and this in turn increases dopamine. Positive expectations in all individuals, not just those with Parkinson’s disease, are associated with an increase in dopamine. The Parkinson’s disease placebo study shows how expectations can influence health outcomes including brain changes. The psychological factor of expectation has consistently been shown to play an important role in health treatments.

Thought Question: What is an example from your experience where a positive expectation of change has made a difference in your health or life?

Improving Health and Managing Stress

In addition to listing the major causes of death, the WHO also has identified risk factors related to death worldwide (WHO, 2010). Many of these risk factors have a strong behavioral component. For example, tobacco use is the second major risk factor and is related to 9% of the deaths worldwide. Tobacco use is a risk because it leads to a number of disorders including lung cancer. It has a strong behavioral component in that peer pressure can lead to its adoption. Also, individuals can choose to modify their tobacco use.

The first leading risk factor worldwide is high blood pressure, which is associated with 13% of deaths globally. As noted, the second risk factor is tobacco use (9%) followed by high blood glucose (6%), which is associated with diabetes and other disorders. The fourth risk factor is physical inactivity, which is associated with 6% of deaths worldwide. The fifth risk factor is being overweight and obese, which is associated with 5% of deaths worldwide.

These five risk factors are interrelated such that inactivity can be associated with being overweight and developing diabetes. In this manner, inactivity is estimated to be a 30% cause of heart disease. Unlike the patterns of communicable disease seen in the early part of the 1900s, which were reduced through public works projects such as better water system and sewage treatment, these five risk factors involve behavioral factors.

Physical activity is one of the easiest stress reduction and life-increasing activities that we as humans engage in. Physical activity comes in so many forms. You can run, canoe, swim, dance, as well as walk, or work in the garden to name a few. Most of the time physical activity makes us feel better and improves our mood. Given the right amount of exercise, our bodies produce endorphins, the brain-made, opiate-like biochemicals that leave us feeling good.

In 1979, researchers began to study 2,235 men from 45 to 59 years of age in South Wales of the United Kingdom (Elwood et al., 2013). They followed these men for the next 30 years, including cognitive performance tests in 2004. This study examined the effects of a healthy lifestyle on disease and cognitive functioning. Five items were studied in terms of a healthy lifestyle. These healthy activities included not smoking, eating fruits and vegetables, engaging in physical activity, not being overweight, and a low to moderate intake of alcohol. The results showed that a healthy lifestyle is associated with a 50% reduction in diabetes, 50% reduction in vascular disease, and a 60% reduction overall in all causes of mortality. Further, there was a 60% reduction in cognitive decline with aging. These results are similar to previous studies in the US with both males and females.

In their review of the literature, WHO found strong evidence that compared to less active adult men and women, individuals who are more active have lower rates of all causes of mortality, including coronary heart disease, high blood pressure, stroke, diabetes, metabolic syndrome, colon cancer, breast cancer, and depression. Strong evidence also exists to support the conclusion that, compared to less active people, physically active adults and older adults exhibit a higher level of cardiorespiratory and muscular fitness, have a healthier body mass and composition, and a biomarker profile that is more favorable for preventing cardiovascular disease and type 2 diabetes and for enhancing bone health.

One minute of vigorous intensity activity provides benefits roughly equal to two minutes of moderate intensity activity. The two intensities can be mixed.

Based on their review of the literature, the WHO made specific activity recommendations for three age levels. For those from 5 to 17 years of age, they recommend 60 minutes of physical activity daily. This can be playing sports, hiking, and other activities with family, friends, and school. They further conclude that more than 60 minutes of physical activity will provide additional health benefits. In order to strengthen muscle and bone, vigorous intensive exercise should be performed three times a week.

For those in the 18-to 64-year age range, they recommend at least 150 minutes of activity each week. Likewise, increasing this amount has additional health benefits. From their review, the WHO concludes that an increase in physical activity is correlated with a reduction in cardiovascular health problems, including heart attack and stroke. Physical activity also reduces the risk of diabetes and helps with weight control. Exercise has also been shown to improve brain function and performance on cognitive tests (Raichlen & Alexander, 2017; Voss, Vivar, Kramer, & van Praag, 2013).

As people enter the age of 65 and over, the results of previous inactivity become more apparent including cardiovascular problems, obesity, and diabetes. For those more than 65 who are healthy, the same recommendations hold as for the 18—64 age group. Actually, WHO suggests that for those more than 65, the benefits of physical activity are greater since inactivity can be more detrimental at this age. For those more than 65 with problems in exercising, the emphasis should be on enhancing balance and preventing falls.

In summary, a number of studies have sought to determine what simple things you can do to promote psychological and physical health throughout your life. Some of these are not complicated, such as exercise, eating good food, and having good social relationships. Working at a job you feel good about is also an important contributor to a healthy life. Combining these factors such as eating well and exercising show synergistic positive effects on the brain (van Praag, 2009).

Meditation

Over the past 50 years, relaxation and meditation have been shown to play a role in stress reduction and health promotion. Relaxation training has been shown to be an important component for promoting both mental and physical health. Likewise, meditation is becoming an important component in treatment. The most widely studied form of meditation is mindfulness (Wielgosz, Goldberg, Kral, Dunne, & Davidson, 2019). Although mindfulness has many different meanings in psychological and spiritual literature, it is commonly referred to as both a practice and a state of mind. The basic procedure is that during meditation one simply watches one’s thoughts or bodily experiences. The task is not to be distracted by one’s reactions to these but to allow both the perceptions and the reactions to come and go. The focus is on viewing the present in a nonjudgmental manner without being distracted by what one is observing.

One review of the meditation research examined the effects of mindfulness meditation on psychological health (Keng, Smoski, & Robins, 2011). Most of this research was conducted with individuals who were not seeking psychological treatment for specific problems. The overall general finding was that mindfulness meditation was associated with positive psychological health. Positive psychological health included the person feeling better, showing less psychological distress, and a greater ability to experience and regulate his or her emotional life.

In addition to mindfulness, which involves nonreactive monitoring of the contents of experience, there are focused meditations that has the individual voluntarily focus on a particular object or process. The object of attention can be a visual image, a repeated sound, or even your own breath. Using both types of meditation, researchers have sought to determine how meditation affects the brain (Lutz, Slagter, Dunne, & Davidson, 2008). Using fMRI, experts in a focused meditation showed less activation of the amygdala during the meditation than did novice meditators, which is associated with less negative emotionality. In terms of nonreactive meditation, those who had been meditating for more than ten years showed EEG differences from those who were less experienced. These differences included greater synchrony in different areas of the brain. Several studies have also shown that the anterior cingulate cortex and the insula are involved in meditation. These areas of the brain are involved in emotional regulation and our sense of self. The current perspective is described in the box: The World Is Your Laboratory: Complementary and Alternative Medicine.

The World Is Your Laboratory: Complementary and Alternative Medicine

Initially, the terms complementary medicine and alternative medicine referred to those treatments that were not taught in medical school. These techniques could include procedures such as acupuncture, meditation, hypnosis, diet, biofeedback, yoga, relaxation, and exercise. In 1993, an article was published in the New England Journal of Medicine showing that one in three people in the United States used some form of alternative treatment during the past year (Eisenberg et al., 1993).

At about the same time, the United States National Institutes of Health (NIH) established a center for the study of complementary and alternative medicine. The National Center for Complementary and Alternative Medicine (NCCAM) developed research to understand the safety and effectiveness of these approaches. Reflecting the continued use of these procedures alongside traditional approaches, NCCAM changed its name to the National Center for Complementary and Integrative Health (NCCIH) in 2015. Today, many major medical centers around the country offer integrative medicine.

One research study examined how acupuncture can reduce pain in carpal tunnel syndrome. Acupuncture to the correct site for 16 sessions compared with sham procedures showed a reduction in pain. With actual acupuncture, there were changes in the brain areas related to sensory processing (Maeda et al. 2017). Acupuncture has also been shown to reduce hot flashes during menopause (Avis et al., 2016). Overall, acupuncture has been effective with a number of disorders.

Cardiovascular disease is the leading cause of death in the United States. Various forms of stress can also contribute to this disorder. In addition, African Americans are at greater risk for cardiovascular problems than other groups. In one study, African Americans who had cardiovascular disease were taught a meditation technique or offered health education (Schneider et al., 2012). The participants in these two groups were followed at various intervals. During a five-year period, those who practiced the meditation procedure showed a 48% risk reduction in deaths, and lower blood pressure as well as a reduction in anger expression. Meditation has also been shown to be effective in the treatment of insomnia (Ong et al., 2014).

At this point, it is critical that integrative health procedures, like all treatment procedures, receive careful research to determine their effectiveness and which individuals they work with. The evidence thus far is that a number of procedures that use psychological principles can affect and improve our health.

Thought Question: What is the significance of changing the terminology from “complementary and alternative medicine” to “integrative health”? Think about a disorder you or a friend or family member has had and what kinds of treatment you would include under the umbrella of “integrative health.”

CONCEPT CHECK

1. What is the role of psychological and behavioral components in the major causes of death today?

a. How has that changed over the last 100 years?

b. Currently, what are the leading health risks worldwide?

c. What are four steps you can start taking now to improve your health and manage stress?

2. What is the placebo response? How is expectation related to it?

a. Expectation?

3. What is mindfulness meditation? What role can it play in improving health and managing stress?

Summary

Learning Objective 1. Define stress and the ways people experience and respond to stress.

Stress is commonly defined as a response that is brought on by any situation that threatens a person’s ability to cope. Scientists speak of the stress response as a response to a critical situation that allows an organism to avoid danger or reduce other types of threat.

Psychological factors play a critical role in how we experience stress. We can experience stress both from real situations and from our expectations of what might happen. Even after the event has passed, our body can continue to display characteristics of stress. If you perceive there is danger, your body immediately reacts. Adrenalin is released and blood is sent to your legs to supply biochemical substances so that you can run. To help in the process, your heart rate and lung capacity is increased. Processes that you don’t need such as the digestion of food or your sexual responses are inhibited. This has been referred to as the fight or flight response.

Learning Objective 2. Discuss the early approaches to the study of stress.

In the early 1900s, the French physiologist Claude Bernard realized that the brain had circuits that were specialized for monitoring and controlling internal events that he referred to as the internal milieu. These internal states included physiological processes such as thirst, temperature, and metabolism. This idea of an internal monitoring of bodily states underlies the development of the concept of homeostasis as described previously.

In 1915, Walter Cannon at Harvard developed the concept of homeostasis to reflect the manner in which a physiological system tended to center on a set point. Homeostasis is the process in which the body keeps itself in balance. Like a thermostat, if you become too hot, your body sweats to reduce heat by processes such as sweating and if you become cold, your metabolism is increased.

Another major figure in the history of stress research was the Hungarian endocrinologist Hans Selye who worked at the University of Montreal. His work in the 1930s helped to set up the connection between stress and the development of diseases. One of Selye’s early findings was that the body reacts similarly to a variety of different stressors. Selye called this response the General Adaptation Syndrome (GAS).

Bruce McEwen has begun to suggest a more flexible set of processes that involve the brain in the regulation of the body’s reaction to stress. McEwen begins by suggesting that part of the problem in understanding stress is the ambiguous meaning of the term stress. He suggests that the term stress be replaced with the term allostasis. Allostasis refers to the body’s ability to achieve stability through change. His view emphasizes the brain as the means of stability, which can be accomplished in a number of different ways. That is, there is not just one single response to stress according to McEwen.

Learning Objective 3. Describe the autonomic nervous system (ANS).

The autonomic nervous system (ANS) consists of the neural circuitry that controls the body’s physiology. This physiology involves the smooth muscle organs and tissues as well as the other organs such as the heart, gastrointestinal, genital, and lung systems (see Figure 11-2). Along with the endocrine system, the ANS manages continuous changes in blood chemistry, respiration, circulation, digestion, reproductive status, and immune responses. Two branches of the ANS are the sympathetic nervous system and the parasympathetic nervous system.

Learning Objective 4. Discuss the research that suggests that social relationships provide a protective mechanism in improving health and managing stress.

Research suggests that people with social support live longer, whereas those who are isolated display more detrimental health problems. For example, there are a variety of studies that show a strong relationship between social isolation and subsequent cardiovascular morbidity. Overall, social support reduces cardiovascular reactivity to acute stress, and lack of social support is associated with increased resting levels of sympathetic activation. Thus, lack of social support may itself be a stressor.

Based on the studies examining social relationships and health, Taylor and Gonzaga (2006) developed a social shaping hypothesis. This hypothesis suggests that early social relationships can shape the manner in which a person’s biological, social, and behavioral processes respond to a variety of situations including stressful ones. For these researchers, social shaping has three functions.

1. Early relationships can calibrate how those systems involved in stress responses will develop.

2. Social relationships help to regulate the stress response in terms of day-to-day experiences. Social relationships tend to buffer stress responses, whereas the lack of social relationships tends to exaggerate the responses.

3. Social relationships can serve as a source of information as to the nature of the present environment. The information can be presented directly or indirectly.

Learning Objective 5. Explain the role of behavioral and emotional processes in the expectation of health outcomes.

During the 20th century, psychologists became health care professionals. This represents an understanding that treatment of most disorders involves a strong behavioral and emotional component. In fact, different individuals recover differently from the same disorder. This has led to both research and treatment studies involving psychological factors and health. Overall, it became clear that culture, lifestyle, as well as physical components such as genetics needed to be considered to understand health and disease.

Study Resources

Review Questions

1. In the study of stress, researchers Selye and McEwen both referred to the paradox that the same physiological and stress responses that protect and restore the body can also damage it. In terms of that paradox, please answer the following questions:

a. How did our stress responses evolve, and what led to the paradox?

b. How do our stress responses protect and restore our body and mind?

c. How can our stress responses damage our body and mind?

2. A description of physiology—both human and animal—and its response to stress makes up a large portion of this chapter in an introductory psychology book. How would you characterize the overall relationship among our physiology, psychology, and responses to stress? What are some specific examples of the interrelationships?

3. This chapter has described a number of concepts that are related to adapting to and managing stress successfully. These concepts include control, positive expectations, and being exposed to stressors early and gradually. What other concepts from the chapter and your experience would you include in this list? What overall label and description would you give to this category of concepts?

4. From what you have read in this chapter and learned in your course about PTSD, develop a statement of your understanding of PTSD including causes; psychological, neurological, emotional, and behavioral symptoms; individual differences; and treatment approaches. What questions do you still want answers to about PTSD?

5. Health is something we think about every day in one way or another. Is health only the absence of disease? From what you have read in this chapter, how would you define health from the following seven perspectives: cultural, social, individual, cognitive/emotional, physiological, brain, and genetic?

For Further Reading

✵ McEwen, B. (2002). The End of Stress as We Know It. New York: Dana Foundation Press.

✵ Sapolsky, R. (2004). Why Zebras Don’t Get Ulcers, 3rd edition. New York: Henry Holt & Co.

Web Resources

✵ Human stress—https://www.wnycstudios.org/podcasts/radiolab/episodes/91580-stress

✵ Veteran PTSD—https://www.ptsd.va.gov/index.asp

Key Terms and Concepts

allostasis

allostatic load

allostatic systems

autonomic nervous system (ANS)

fight or flight response

General Adaptation Syndrome (GAS)

HPA (hypothalamic pituitary adrenal) pathway

mindfulness

parasympathetic nervous system

post-traumatic stress disorder (PTSD)

SAM (sympathetic adrenal medullary) system

social shaping hypothesis

stress

stress response

sympathetic nervous system

tend and befriend response

uncontrollable stress resilience