Chapter 11-12: The Nature and Symptoms of Pain PDF

k PART V PHYSICAL SYMPTOMS: PAIN AND DISCOMFORT 11 THE NATURE AND SYMPTOMS OF PAIN...

k PART V PHYSICAL SYMPTOMS: PAIN AND DISCOMFORT 11 THE NATURE AND SYMPTOMS OF PAIN What Is Pain? dislike it and try to avoid it. But being able to sense pain The Qualities and Dimensions of Pain is critical to our survival—without it, how would we know k Perceiving Pain when we are injured? We could have a sprained ankle or k an ulcer, for instance, without realizing it, and not seek Theories of Pain treatment. And how would we know we are about to be Early Theories of Pain injured, such as when we approach a hot flame without The Gate-Control Theory of Pain seeing it? Pain serves as a signal to take protective action. Are there people who do not feel pain? Yes—several Biopsychosocial Aspects of Pain disorders can reduce or eliminate the ability to sense Neurochemical Transmission pain. People with a condition called congenital insensitivity and Inhibition of Pain to pain, which is present from birth, may report only a Personal and Social Experiences and Pain “tingling” or “itching” sensation when seriously injured. Emotions, Coping Processes, and Pain A young woman with this disorder Assessing People’s Pain seemed normal in every way, except that she had never Self-Report Methods felt pain. As a child she had bitten off the tip of her Behavioral Assessment Approaches tongue while chewing food, and had suffered third- Psychophysiological Measures degree burns after kneeling on a hot radiator to look out of a window. When examined by a psychologist... Pain in Children in the laboratory, she reported... no pain when parts Pain and Children’s Sensory and Cognitive of her body were subjected to strong electric shock, Development to hot water at temperatures that usually produce Assessing Pain in Children reports of burning pain, or to a prolonged ice-bath. Equally astonishing was the fact that she showed no changes in blood pressure, heart rate, or respiration PROLOGUE when these stimuli were presented. Furthermore, she could not remember ever sneezing or coughing, the “Wouldn’t it be wonderful never to experience pain,” gag reflex could be elicited only with great difficulty, many people have thought when they or others they have and the cornea reflexes (to protect the eyes) were known were suffering. Pain hurts, and people typically absent. (Melzack, quoted in Bakal, 1979, p. 141) 288 k  k Chapter 11 / The Nature and Symptoms of Pain 289 This disorder contributed to her death at the age of as “sharp” and others as “dull,” for example—and sharp 29. People with congenital insensitivity to pain often pains can have either a stabbing or pricking feel. Some die young because injuries or illnesses, such as acute pains involve a burning sensation, and others have a appendicitis, go unnoticed (Chapman, 1984; Sarasola cramping, itching, or aching feel. And some pains are et al., 2011). throbbing, or constant, or shooting, or pervasive, or Health psychologists study pain because it influ- localized. Often the feelings we experience depend on ences whether individuals seek and comply with medical the kinds of irritation or damage that has occurred treatment and because being in pain can be very distress- and the location. For instance, when damage occurs ing, particularly when it is intense or enduring. In this deep within the body, people usually report feeling chapter we examine the nature and symptoms of pain, a “dull,” “aching,” or “throbbing” pain; but damage and the effects it has on its victims when it is severe. produced by a brief noxious event to the skin is As we consider these topics, you will find answers to often described as “sharp” (Schiffman, 1996; Tortora & questions you may have about pain. What is pain, and Derrickson, 2012). what is the physical basis for it? Can people feel pain The painful conditions people experience also differ when there is no underlying physical disorder? Do psy- in how the pain originates and how long it lasts. We will chosocial factors affect our experience of pain? Because consider two dimensions that describe these differences, pain is a subjective experience, how do psychologists beginning with the degree to which the origin of the pain assess how much pain a person feels? can be traced to tissue damage. WHAT IS PAIN? Organic Versus Psychogenic Pain The pain we experience that is clearly linked to tissue Pain is the sensory and emotional experience of pressure or damage is described as organic pain. For discomfort, which is usually associated with actual or example, damage can arise from a burn or sprain; threatened tissue damage or irritation (AMA, 2003). pressure can develop when the opening in a disc of the Virtually all people experience pain and at all ages—from spine narrows and squeezes the spinal cord. Narrowing in k the pains of birth for mother and baby, to those of colic k the spine can occur when discs degenerate—a condition and teething in infancy, to those of injury and illness that is affected by genetics (Battié et al., 2007). For in childhood and adulthood. Some pain can become other pains, medical examinations fail to find an organic chronic, as with arthritis, problems of the lower back, basis. Because the discomfort in these pains could migraine headache, or cancer. result from psychological processes, it may be described People’s experience with pain is important for as psychogenic pain. One of your authors (EPS) once several reasons. For one thing, no medical complaint witnessed a possible example of psychogenic pain in is more common than pain—it accounts for more than a schizophrenic man: he claimed—and really looked 80% of all visits to physicians (Gatchel et al., 2007). As we like—he was “feeling” stings from being “shot by enemy saw in Chapter 9, people are more likely to seek medical agents with ray guns.” treatment without delay if they feel pain. Also, severe Not long ago, researchers considered organic and and prolonged pain can come to dominate the lives of psychogenic pain to be separate entities, with psy- its victims, impairing their general functioning, ability chogenic pain not involving “real” sensations. As pain to work, social relationships, and emotional adjustment. researcher Donald Bakal has noted, a practitioner’s ref- Last, pain has enormous social and economic effects on erence to pain as “psychogenic” all societies of the world. Among Americans 18 years of age or older, about 27% experience joint pain and was taken to mean “due to psychological causes,” 28% experience low back pain in a given 3 month period which implied that the patient was “imagining” his (NCHS, 2014). Headache, back, and joint pain are very pain or that it was not really pain simply because an common causes of work absence and disability in the organic basis could not be found. Psychogenic pain United States, and each year costs tens of billions of is not experienced differently, however, from that dollars in lost productivity, treatment, and disability arising from physical disease or injury. Psychogenic payments (Thorn & Walker, 2011). and organic pain both hurt. (1979, p. 167) Researchers now recognize that virtually all pain expe- riences involve an interplay of both physiological and THE QUALITIES AND DIMENSIONS OF PAIN psychosocial factors, and the dimension of pain involving Our sensations of pain can be quite varied and have organic and psychogenic causes is viewed as a continuum many different qualities. We might describe some pains rather than a dichotomy. k  k 290 Part V / Physical Symptoms: Pain and Discomfort Different pain experiences simply involve different the aid of painkillers or other treatments prescribed by mixtures of organic and psychosocial factors. A mixture a physician. If a similar painful condition occurs in the of these factors seems clear in the findings that some future, it is not connected in a direct way to the earlier people with tissue damage experience little or no pain, experience. This is the case for most everyday headaches, others without damage report severe pain, and the role for instance, and for the pain typically produced by of psychological factors in people’s pain increases when such conditions as toothaches and muscle strains, but the condition is long-lasting (Thorn & Walker, 2011; Turk, accidental wounds and surgeries can produce long-term Wilson, & Swanson, 2012). When people experience long- pain if they involve damage to peripheral nerves or term pain as a part of excessive concerns for their physical concussions (Bruce et al., 2014; Seifert, 2013). symptoms or health, psychiatrists diagnose the condition Acute pain refers to the discomfort people expe- as a somatic symptom disorder (Kring et al., 2012). Usually, rience with temporary painful conditions that last less the person’s symptoms are medically unexplained. Keep than about 3 months (Mann & Carr, 2006; Williams, in mind, however, that failing to find a physical basis 2010). Patients with acute pain often have higher than for one’s pain does not necessarily mean there is none. normal levels of anxiety while the pain exists, but their For instance, we now know that persistent pain produces distress subsides as their conditions improve and their structural and functional changes to the nervous system, pain decreases (Fordyce & Steger, 1979). making the person hypersensitive to pain stimuli (Thorn When a painful condition lasts longer than its & Walker, 2011; Woolf, 2011). Unfortunately, many health expected course or for more than a few months, it is care workers still think pain that has no demonstrated called chronic, and is not just a longer-lasting acute pain. physical basis is purely psychogenic, and their patients People with chronic pain continue to have high levels of struggle to prove that the pain isn’t just in their heads. anxiety and tend to develop feelings of hopelessness and helplessness because various medical treatments have Acute Versus Chronic Pain not helped. Pain interferes with their daily activities, Experiencing pain either continuously or frequently goals, and sleep; it can come to dominate their lives over a period of many months or years is different from (Turk, Wilson, & Swanson, 2012). These effects can be seen in the following passage: k having occasional and isolated short-term bouts with k pain. The length of experience an individual has had Pain patients frequently say that they could stand their with a painful condition is an important dimension in pain much better if they could only get a good night’s describing his or her pain. sleep.... They feel worn down, worn out, exhausted. Most of the painful conditions people experience They find themselves getting more and more irritable are temporary—the pain arrives and then subsides in with their families, they have fewer and fewer friends, a matter of minutes, days, or even weeks, often with and fewer and fewer interests. Gradually, as time goes Bongarts/Getty Images The acute pain this football (soccer) player feels will probably diminish in minutes, hours, or days. k  k Chapter 11 / The Nature and Symptoms of Pain 291 by, the boundaries of their world seem to shrink. They PERCEIVING PAIN become more and more preoccupied with their pain, less and less interested in the world around them. Of the several perceptual senses the human body uses, Their world begins to center around home, doctor’s the sense of pain has three unique properties (Chapman, office, and pharmacy. (Sternbach, quoted in Bakal, 1984; Melzack & Wall, 1982). First, although nerve fibers 1979, p. 165) in the body sense and send signals of tissue damage, the receptor cells for pain are different from those of Several findings about sleep and pain are important: other perceptual systems, such as vision, which contain First, a day with high levels of pain tends to be followed specific receptor cells that transmit only messages about by a night of poor sleep, and poor sleep tends to a particular type of stimulation—light, for the visual be followed by heightened pain the next day (O’Brien system. The body has no specific receptor cells that et al., 2011). Second, although pain itself can impair transmit only information about pain. Second, the body sleep, depression, intrusive thoughts, and worry do, too senses pain in response to many types of noxious stimuli, (Nicassio et al., 2012; Smith et al., 2000). Third, long- such as physical pressure, lacerations, and intense heat term sleep deprivation increases people’s negative affect, or cold. Third, pain perception almost always includes sensitivity to pain, and amount of pain experienced in a strong emotional component. As we are about to future weeks (Hamilton et al., 2008; Kundermann et al., see, perceiving pain involves a complex interplay of 2004; Quartana et al., 2010). Many people with chronic physiological and psychological processes. pain leave their jobs for emotional and physical reasons and must live on reduced incomes at the same time that The Physiology of Pain Perception their medical bills are piling up. The experience of pain To describe the physiology of perceiving pain, we will is very different when the condition is chronic than when trace the bodily reaction to tissue damage, as when the it is acute. body receives a cut or burn. The noxious stimulation The effects of chronic pain also depend on whether instantly triggers chemical activity at the site of injury, the underlying condition is benign (harmless) or is releasing chemicals—which include serotonin, histamine, malignant (injurious) and worsening and whether the k and bradykinin—that promote immune system activity, k discomfort exists continuously or occurs in frequent and cause inflammation at the injured site, and activate intense episodes. These factors define three types of endings of nerve fibers in the damaged region, signaling chronic pain (Turk, Meichenbaum, & Genest, 1983): injury. Afferent neurons of the peripheral nervous system 1. Chronic-recurrent pain stems from benign causes carry the signal of injury to the spinal cord, which carries and involves repeated and intense episodes of pain the signal to the brain. The afferent nerve endings that separated by periods without pain. Two examples of respond to pain stimuli and signal injury are called chronic-recurrent pain are migraine headaches and nociceptors (Mann & Carr, 2006; Tortora & Derrickson, tension-type (muscle-contraction) headaches; another 2012). These fibers exist in every body tissue except example is myofascial pain, a syndrome that typically the brain. involves pain in the jaw and muscles of the head and Pain signals are carried by afferent peripheral fibers neck (AMA, 2003). of two types: A-delta and C fibers. A-delta fibers are 2. Chronic-intractable-benign pain refers to discomfort coated with myelin, a fatty substance that enables that is typically present all of the time, with varying neurons to transmit impulses very quickly. These fibers levels of intensity, and is not related to an underlying are associated with sharp, well-localized, and distinct malignant condition. Sometimes chronic low back pain pain experiences. C fibers transmit impulses more has this pattern. slowly—because they are not coated with myelin—and seem to be involved in experiences of diffuse dull, 3. Chronic-progressive pain is characterized by con- tinuous discomfort, is associated with a malignant burning, or aching pain sensations (Mann & Carr, 2006; condition, and becomes increasingly intense as the Tortora & Derrickson, 2012). Signals from A-delta and underlying condition worsens. Two malignant condi- C fibers follow different paths when they reach the tions that frequently produce chronic-progressive pain brain (Bloom, Lazerson, & Hofstadter, 1985; Guyton, are rheumatoid arthritis and cancer. 1985). The brain regions we’ll mention are shown in Figures 2-3 and 2-4. A-delta signals, which reflect sharp As we shall see later in this chapter and in the next pain, go to motor and sensory areas; this suggests that one, the type of pain people experience influences their these signals receive special attention in our sensory psychosocial adjustment and the treatment they receive awareness, probably so that we can respond to them to control their discomfort. (Go to.) quickly. C fiber signals, which reflect burning or aching k  k 292 Part V / Physical Symptoms: Pain and Discomfort HIGHLIGHT Acute Pain in Burn Patients We often hear or read about people greatest during “tankings,” in which the patient being seriously burned, such as in a fire or through is lowered on a stretcher into a large tub. The scalding. Over 480,000 burn injuries receive medical old dressings are removed and the patient is treatment each year in the United States (ABA, 2015). gently scrubbed to remove encrusted medication. People with serious burns suffer acute pain both from Debridement, which is usually necessary during their injuries and from the treatment procedures that the early weeks of hospitalization, involves the must be performed. vigorous cutting away of dead tissue in burned Medical workers describe the severity of a burn areas. The process, which may last for more than on the basis of its location and with two measures an hour and involve several people working on of its damage (AMA, 2003; MedlinePlus, 2015)—the different parts of the body simultaneously, ends percentage of skin area affected and the depth of the when fresh medication and new dressings are burn, expressed in three “degrees”: applied. (Wernick, 1983, p. 196)11-1 1. First-degree burns involve damage restricted to the These and many other painful medical procedures occur epidermis, or outermost layer of skin. The skin turns very frequently, and burn patients must also do exercises red, but does not blister—as, for example, in most for physical or occupational therapy. The rehabilitation cases of sunburn. phase begins at about the time of discharge from the 2. Second-degree burns are those that include damage to hospital and continues until the scar tissue has matured. the dermis, the layer below the epidermis. These burns Although the pain has now subsided, itching in the are quite painful, often form blisters, and can result healed area (which should not be scratched) can be a from scalding and fire. source of discomfort, as can using devices and doing 3. Third-degree burns destroy the epidermis and dermis exercises to prevent scarring and contractures (skin k shrinkage that can restrict the person’s range of motion). k down to the underlying layer of fat, and may extend to the muscle and bone. These burns usually result from Analgesic medication is the main approach for fire. When third-degree burns damage nerve endings, controlling acute pain in the hospital (AMA, 2003). But there is generally no pain sensation in these regions psychological approaches can also help burn patients initially. cope with their pain so that they need less medication. Robert Wernick (1983) used a program of psychological Practitioners assess the depth of a burn by its appearance preparation with adult severe-burn patients to enhance and the sensitivity of the region to pain. the patients’ sense of informational, behavioral, and Hospital treatment for patients with severe burns cognitive control over their discomfort, especially with progresses through three phases (AMA, 2003; Wer- regard to the tanking and debridement procedures. nick, 1983). The first few days after the burn is called Although these patients were not specifically asked to the emergency phase, during which medical staff assess reduce their use of drugs, they subsequently requested the severity of the burn and work to maintain the much less medication than patients in a comparison patient’s body functions and defenses, such as in pre- (control) group who received the standard hospital venting infection and balancing fluids and electrolytes preparation. Similar preparation methods have also (substances that conduct electrical messages). The been successful with children (Tarnowski, Rasnake, & acute phase extends from the end of the emergency phase Drabman, 1987). Another approach that is effective until the burned area is covered with new skin. This for children and adults distracts their attention during process can take from several days to several months, debridement or other painful procedure with a virtual depending on the severity of the burn. The pain is con- reality method in which patients wear a helmet and stant during most or all of this phase, particularly when earphones that present scenes and block visual and nerve endings begin to regenerate in third-degree burns. auditory experience from the hospital world (Hoffman Suffering is generally et al., 2011). k  k Chapter 11 / The Nature and Symptoms of Pain 293 pain, terminate mainly in the brainstem and forebrain, (AMA, 2003; Melzack & Wall, 1982; Tortora & Derrickson, with their remaining impulses connecting with a diffuse 2012). Sometimes neuralgia begins after an infection, network of neurons. Signals of dull pain are less likely to such as of shingles (herpes zoster), in the nerve. In command our immediate attention than those of sharp one form of this syndrome, called trigeminal neuralgia, pain, but are more likely to affect our mood and general excruciating spasms of pain occur along the trigeminal emotional and motivational states. nerve that projects throughout the face. Episodes of So far, the description we have given of physiological neuralgia occur very suddenly and without any apparent reactions to tissue damage makes it seem as though the cause, and attacks can often be provoked more readily by process of perceiving pain is rather straightforward. But innocuous stimuli than by noxious ones. For instance, it actually isn’t. One phenomenon that complicates the drawing a cotton ball across the skin can trigger an attack, picture is that pains originating from internal organs but a pin prick does not. are often perceived as coming from other parts of the Causalgia, also called “complex regional pain syn- body, usually near the surface of the skin. This is called drome,” typically involves recurrent episodes of severe referred pain (AMA, 2003; Tortora & Derrickson, 2012). burning pain that often can be triggered by minor stim- The pain people often feel in a heart attack provides a uli, such as clothing resting on the area or a puff of widely known example of this phenomenon: the pain is air (AMA, 2003; Harden & Bruehl, 2006; Melzack & Wall, referred to the shoulders, pectoral area of the chest, and 1982). A patient with causalgia might report, for instance, arms. Other examples of referred pain include: that the pain feels “like my arm is pressed against a hot stove.” In this syndrome, the pain feels as though it Pain perceived in the right shoulder resulting from a originates in a region of the body where the patient had problem in the liver or gallbladder. at some earlier time been seriously wounded, such as Pain in the upper back originating in the stomach. by a gunshot or stabbing, but only a small minority of Pain in the neck and left shoulder that results from a severely wounded patients develop causalgia—and for problem in the diaphragm. those who do, the pain persists long after the wound has Referred pain results when sensory impulses from an healed and damaged nerves have regenerated. Episodes of causalgia can be unpredictable and often occur spon- k internal organ and the skin use the same pathway k in the spinal cord (AMA, 2003; Tortora & Derrickson, taneously. 2012). Because people are more familiar with sensations Phantom limb pain is an especially puzzling phe- from the skin than from internal organs, they tend to nomenon because the patient—an amputee or someone perceive the spinal cord impulses as coming from the whose peripheral nervous system is irreparably skin. Another issue that complicates our understanding damaged—feels pain in a limb that either is no longer of pain perception is that people feel pains that there or has no functioning nerves (AMA, 2003; Melzack & have no detectable physical basis, as the next section Katz, 2004). After an amputation, for instance, most discusses. patients claim to have sensations of their limb still being there—such as by feeling it “move”—and most of these individuals report feeling pain, too. Phantom limb Pain with No Detectable Current Cause pain generally persists for months or years, can be quite Some pains people experience are curious because severe, and sometimes resembles the pain produced medical exams find no current cause for them—for by the injury that required the amputation. Individuals instance, no noxious stimulus is present. These pains with phantom limb pain may experience either recurrent are usually classified as neuropathic pain which result or continuous pain and may describe it as shooting, from current or past disease or damage in peripheral burning, or cramping. For example, many patients who nerves (AMA, 2003; Mann & Carr, 2006). Three common feel pain in a phantom hand report sensing that the neuropathic pain syndromes are neuralgia, causalgia, hand is tightly clenched and its fingernails are digging and phantom limb pain. These syndromes often begin into the palm. with tissue damage, such as from disease or injury, Why do people feel pain when no noxious stimula- but the pain persists long after healing is complete, tion is present? Although the answer probably relates to may spread and increase in intensity, and may become neural damage that preceded the neuropathic condition, stronger than the pain experienced with the initial it is unclear why most patients who suffer obvious neural damage (AMA, 2003; Melzack & Wall, 1982). damage do not develop these pain syndromes. This Neuralgia is an extremely painful syndrome in which puzzle is far from solved, but the explanation will almost the patient experiences recurrent episodes of intense surely involve both physiological and psychological shooting or stabbing pain along the course of a nerve factors. k  k 294 Part V / Physical Symptoms: Pain and Discomfort The Role of the “Meaning” of Pain if they “wanted something to relieve it.” Some years later, Beecher conducted a similar examination—this Some people evidently like pain—at least under some, time with civilian men who had just undergone surgery. usually sexual, circumstances—and are described as Although the surgical wounds were in the same body masochists. For them, the meaning of pain seems to be regions as those of the soldiers, the soldiers’ wounds different from what it is for most people. They may had been more extensive. Nevertheless, 75% of the have come to like pain through classical conditioning, civilians claimed to be in “moderate” or “severe” pain that is, by participating in, or viewing, activities that and 83% requested medication. (The painkillers used for associate pain with pleasure in a sexual context (Wincze, the soldiers and civilians were narcotics.) 1977). Early evidence for a role of classical conditioning Why did the soldiers—who had more extensive came from research with animals. For example, Pavlov wounds—perceive less pain than the civilians? Beecher (1927) found that dogs’ negative reaction to aversive described the meaning the injuries had for the soldiers, stimuli, such as electric shocks or skin pricks, changed who had experienced almost continuous fire in the prior if the stimuli repeatedly preceded presentation of food. weeks. Of note in these Eventually, the dogs would approach the aversive stimuli, which now signaled that food, not danger, was coming. soldiers was their optimistic, even cheerful, state of Similar processes have now been shown in humans mind.... They thought the war was over for them and that they would soon be well enough to be sent home. (Benedetti et al., 2013; Leknes et al., 2013). Still, It is not difficult to understand their relief on being most people dislike pain and become conditioned to delivered from this area of danger. (1956, p. 1069) fear and avoid it: they learn to avoid activities they fear could produce pain (Turk, Wilson, & Swanson, Their wounds meant to them the end of a disaster. For 2012). This conditioning can make chronic pain patients the civilian surgical patients, however, the wound marked hypersensitive to pain: they notice pain at lower the start of a personal problem, and their condition intensities, rate their pain intensities higher, and become represented a major disruption in their lives. more disabled (Herbert et al., 2014). We discussed in Chapter 9 how people’s perceptions Physician Henry Beecher (1956) described a dramatic of body sensations are influenced by cognitive, social, k example of how the meaning of pain affects people’s and emotional factors—for instance, that they are k experience of it. During World War II, he had examined less likely to notice pain when they are distracted soldiers who had recently been very seriously wounded by competing environmental stimuli, such as while and were in a field hospital for treatment. Of these participating in competitive sports. Psychological factors men, only 49% claimed to be in “moderate” or “severe” play an important role in perceiving pain, and theories pain and only 32% requested medication when asked of pain need to take these factors into account. Corbis-Bettmann For many wounded soldiers, their pain seemed to be reduced by the knowledge that they were going home. k  k Chapter 11 / The Nature and Symptoms of Pain 295 THEORIES OF PAIN Another view of pain, called pattern theory, proposed that there is no separate system for perceiving pain, You have probably seen demonstrations in which and the receptors for pain are shared with other senses, hypnotized people were instructed that they would not such as of touch. According to this view, people feel feel pain—they were then stuck by a pin and did not react. pain when certain patterns of neural activity occur, such When people under hypnosis do not react to noxious as when appropriate types of activity reach excessively stimulation, do they still perceive the pain—only “it high levels in the brain. These patterns occur only with doesn’t matter” to them? Similarly, do patients who seem intense stimulation. Because strong and mild stimuli of relaxed while under the influence of painkillers actually the same sense modality produce different patterns of perceive their pain? Some theories of pain would answer neural activity, being hit hard feels painful, but being “yes” to these questions (Karoly, 1985). Let’s look at two caressed does not. of these theories as we begin to examine how to explain These early theories did not adequately explain pain pain perception. perception (Gatchel et al., 2007; Melzack & Wall, 1982). Pattern theory has been criticized because it requires that the stimuli triggering pain must be intense. Thus, EARLY THEORIES OF PAIN it cannot account for the fact that innocuous stimuli can trigger episodes of causalgia and neuralgia. Perhaps In the early 1900s, the dominant theories of pain took a the most serious problem with the early theories is that very mechanistic view of pain perception. They proposed they do not attempt to explain why the experience of that if an appropriate stimulus activates a receptor, the pain is affected by psychological factors, such as the signal travels to the spinal cord and then the brain, person’s ideas about the meaning of pain, beliefs about and sensation results (Fletcher & Macdonald, 2005; the likelihood of pain, and attention to (or distraction Gatchel et al., 2007; Melzack &Wall, 1982). Specificity theory from) noxious events. Partly because these theories argued that the body has a separate sensory system for overlook the role of psychological factors, they incorrectly perceiving pain—just as it does for hearing and vision. predict that a person must feel just as much pain when k This system was thought to contain its own special hypnotized as when not hypnotized, even though he or k receptors for detecting pain stimuli, its own peripheral she does not show it. Research findings indicate that nerves and pathway to the brain, and its own area of the people who are instructed not to feel pain actually do brain for processing pain signals. But this structure is feel less pain when deeply hypnotized than when in the not correct. normal waking state (Hilgard & Hilgard, 1983). (Go to.) HIGHLIGHT Inducing Pain in Laboratory Research To conduct an experiment dealing with temperature of 2◦ C (35.6◦ F). Water at this temperature pain, researchers sometimes need to create a physically produces a continuous pain that subjects describe as painful situation for human participants. How can they “aching” or “crushing.” A pump circulates the water to accomplish this in a standard way without harming the prevent it from warming in local areas around the arm. people? Several approaches have been used safely; two Before using the apparatus, the person’s arm is common methods are the cold-pressor and muscle-ischemia immersed in a bucket of room-temperature water for procedures (Turk, Meichenbaum, & Genest, 1983). 1 minute. The researcher also explains the cold-pressor procedure, solicits questions, and indicates that some The Cold-Pressor Procedure temporary discoloration of the arm is common. When the procedure is over and the person’s arm is removed from The cold-pressor procedure basically involves immersing the apparatus, the researcher notes that the discomfort the person’s hand and forearm in ice water for a few will decrease rapidly but that it sometimes increases first minutes. A special apparatus is used, like the one for a short while (Turk, Meichenbaum, & Genest, 1983). illustrated in Figure 11-1, so that the researcher can When using this procedure, the person’s pain may be maintain a standard procedure across all people they assessed in several ways, such as by self-ratings or by test. The apparatus consists of an armrest mounted on the length of time he or she is willing to endure the an ice chest filled with water, which is maintained at a discomfort. (continued) k  k 296 Part V / Physical Symptoms: Pain and Discomfort HIGHLIGHT (Continued) arm, inflating it, and maintaining the pressure at a high level—240˜mm Hg (Turk, Meichenbaum, & Genest, 1983). This pressure produces pain without causing damage and can be applied safely for up to 50 minutes or so. Before the procedure begins, the arm is raised over the subject’s Microswitch head for 1 minute to drain excess venous blood. The controls Webbing researcher also informs the person that the procedure photo timer on/off Plastic is safe and harmless, but that it is uncomfortable and cord may produce temporary numbness, throbbing, changes Hinge in arm temperature, and discoloration of the arm and hand. When the cuff is removed, the person raises the arm over his or her head for a few minutes to allow blood flow to return gradually and comfortably. As with the Insulated cold-pressor procedure, measures of muscle-ischemia ice chest pain can include self-ratings and endurance. Another way to measure muscle-ischemia pain uses a variation of the procedure we described; that is, the Water immersion line Counterweight cuff is inflated only to the point when the subject first reports discomfort. This approach assesses the Figure 11-1 Apparatus for the cold-pressor procedure. individual’s pain threshold. Using this method, researchers found that people’s pain thresholds, or cuff pressures at An experiment had people experience the cold- which they reported discomfort, were much (50%) higher pressor procedure twice to test the role of coping for individuals who were listening to a comedy recording methods on pain perception (Girodo & Wood, 1979). (by Lily Tomlin) or practicing relaxation than for people k Before the second procedure, subjects in different groups in control groups (Cogan et al., 1987). Thus, listening to k received different types of training for coping with pain. comedy and practicing relaxation reduces the experience We will focus on two groups. One group was trained to of pain. Other researchers have assessed pain thresholds cope by making positive self-statements; they were taught and found almost no correlation for different types of a list of 20 statements, such as, “No matter how cold it pain within individuals (Janal et al., 1994). This suggests gets, I can handle it,” and “It’s not the worst thing that can that most people cannot be characterized as “stoical” or happen.” For the other group, training involved the same “sensitive” to pain in general. self-statements, but they also received an explanation of how using these statements can enhance their personal Pain Research and Ethical Standards control and help them cope with the pain. Immediately after each cold-pressor procedure, the people rated their When conducting any kind of research with human experience of pain on a scale. Pain ratings decreased from participants, psychologists are obliged to follow the eth- the first to the second test for subjects who received the ical standards set forth by the American Psychological explanation for making the statements and increased for Association (separate guidelines apply for animal stud- those who did not receive the explanation. These results ies). Some of the standards are especially pertinent for suggest that people’s beliefs about the purpose of using research with aversive stimuli. First of all, researchers self-statements may affect their experience of pain. should make certain that any aversive stimulus they use is not actually harmful. In addition, all participants The Muscle-Ischemia Procedure should: The condition of ischemia—or insufficient blood flow—is an important stimulus for the experience of pain when Be informed of any features of the study that might circulation is blocked in internal organs (AMA, 2003). The affect their willingness to participate. pain people experience in a heart attack, for instance, Receive clear answers to their questions. results from poor blood flow in the blood vessels to the Be allowed to choose freely, and without undue heart muscle. influence, whether to participate and whether to quit The muscle-ischemia procedure typically involves at any point. reducing blood flow to the muscles of the arm. This is accomplished by wrapping the cuff of a sphygmo- If a participant is a child, researchers should also obtain manometer (blood pressure testing device) around the consent from an appropriate guardian, usually a parent. k  k Chapter 11 / The Nature and Symptoms of Pain 297 THE GATE-CONTROL THEORY OF PAIN cord from pain fibers (A-delta and C fibers). After these signals pass through the gating mechanism, they activate In the 1960s, Ronald Melzack and Patrick Wall (1965, transmission cells, which send impulses to the brain. When 1982) introduced the gate-control theory of pain the output of signals from the transmission cells reaches perception. This theory integrated useful ideas from a critical level, the person perceives pain; the greater earlier theories and improved on them in several ways, the output beyond this level, the greater the pain particularly by describing a physiological mechanism intensity. by which psychological factors can affect people’s The two diagrams in the figure outline how the experience of pain. As a result, the gate-control theory gating mechanism controls the output of impulses by the can account for many phenomena in pain perception transmission cells. When pain signals enter the spinal that have vexed earlier theories. For instance, it does not cord and the gate is open, the transmission cells send have to predict that hypnotized people must feel noxious impulses freely; but to the extent that the gate is closed, stimulation (Karoly,1985). the output of the transmission cells is inhibited. What controls the opening and closing of the gate? The gate- The Gating Mechanism control theory proposes that three factors are involved: At the heart of the gate-control theory is a neural “gate” 1. The amount of activity in the pain fibers. Activity in these that can be opened or closed in varying degrees, thereby fibers tends to open the gate. The stronger the noxious modulating incoming pain signals before they reach the stimulation, the more active the pain fibers. brain. The theory proposes that the gating mechanism is 2. The amount of activity in other peripheral fibers. Some located in the spinal cord—more specifically, in the peripheral fibers, called A-beta fibers, carry information substantia gelatinosa of the dorsal horns, which are part of about harmless stimuli or mild irritation, such as the gray matter that runs the length of the core of the touching, rubbing, or lightly scratching the skin. Activity spinal cord. Figure 11-2 depicts how the gate-control in A-beta fibers tends to close the gate, inhibiting the process works. You can see in both diagrams of the perception of pain when noxious stimulation exists. figure that signals of noxious stimulation enter the This would explain why gently massaging or applying k gating mechanism (substantia gelatinosa) of the spinal heat to sore muscles decreases the pain. k GATE OPEN GATE CLOSED (high pain) (low pain) Brain Brain +9 +1 From +2 To From –3 To brain brain brain brain From From pain Transmission pain Transmission Gating +9 cells Gating +1 cells fibers fibers mechanism mechanism +6 +6 +1 –2 From other Spinal From other Spinal peripheral fibers cord peripheral fibers cord Figure 11-2 Two diagrams to illustrate gate-control theory predictions when strong pain signals arrive from pain fibers (A-delta and C) at the spinal cord, along with signals from other peripheral fibers (A-beta) and the brain. The diagram on the left depicts what conditions might exist when the gate is open, and the person feels strong pain; the one on the right shows a scenario when the gate is closed, and the person feels little pain. The thick arrows indicate “stimulation” conditions that tend to open the gate and send pain signals through, and the thin ones indicate the opposite, “inhibition,” effect. The numbers that accompany each arrow represent hypothetical values for the degrees of pain stimulation (positive numbers) or inhibition (negative numbers). Pain signals enter the spinal cord and pass through a gating mechanism before activating transmission cells, which send impulses to the brain. (Based on information in Melzack & Wall, 1965, 1982.) k  k 298 Part V / Physical Symptoms: Pain and Discomfort 3. Messages that descend from the brain. Neurons in the pattern of impulses in the network, without the presence brainstem and cortex have efferent pathways to the of a noxious stimulus. spinal cord, and the impulses they send can open or close the gate. The effects of some brain processes, Evidence on the Gate-Control Theory such as those in anxiety or excitement, probably have a general impact, opening or closing the gate for all The gate-control theory has stimulated a great deal inputs from any areas of the body. But the impact of of research and has received strong support from the other brain processes may be very specific, applying to findings of many, but not all, of these studies (Melzack only some inputs from certain parts of the body. & Katz, 2004; Mendell, 2014; Thorn & Walker, 2011). One study, for instance, confirmed the theory’s prediction The idea that brain impulses influence the gating that impulses from the brain can alter the perception mechanism helps to explain why people who are of pain. David Reynolds (1969) conducted this study hypnotized or distracted by competing environmental with rats as subjects. He first implanted an electrode stimuli may not notice the pain of an injury. in the midbrain portion of each rat’s brainstem (see The theory proposes that the gating mechanism Figure 2-3), varying the exact location from one rat to responds to the combined effects of these three factors. the next. Then he made sure they could feel pain by Table 11.1 presents a variety of conditions in people’s applying a clamp to their tails—and all reacted. Several lives that seem to open or close the gate. For instance, days later, he provided continuous, mild electrical anxiety and boredom tend to open the gate, and positive current through the electrode and again applied the emotions and distraction tend to close it. But in the clamp to test whether the current would block pain. minutes after a stressful event ends, the gate seems to Although most of the subjects did show a pain reaction, close—that is, a period of stress-induced pain reduction those with electrodes in a particular region of the occurs (Yilmaz et al., 2010). Melzack later proposed the midbrain—the periaqueductal gray area—did not. The idea of a neuromatrix, a neural network in the brain electrical stimulation had produced a state of not being that integrates information from the senses, cognitive able to feel pain, or analgesia, in these rats. Then Reynolds and emotional areas of the brain, and stress-regulation used these few rats for a dramatic demonstration: he k systems (Melzack & Katz, 2004). In phantom limb pain, k performed surgery on their abdomens while they were the neuromatrix creates the perception of pain from the awake and with only the analgesia produced through electrode stimulation. Studies by other researchers have confirmed that stimulation to the periaqueductal gray Table 11.1 Conditions That Can Open or Close the Pain Gate area can induce analgesia in animals and in humans. Conditions That Open the Gate Moreover, they have determined that morphine works as Physical conditions a painkiller by activating the brainstem to send impulses Extent of the injury down the spinal cord (Chapman, 1984; Melzack & Inappropriate activity level Wall, 1982). Emotional conditions The gate-control theory clearly takes a biopsychoso- Anxiety or worry cial perspective in explaining how people perceive pain. Tension Depression You’ll see many features of this theory as you read the Mental conditions material in the next section. Focusing on the pain Boredom; little involvement in life activities Conditions That Close the Gate BIOPSYCHOSOCIAL ASPECTS OF PAIN Physical conditions Medication Counterstimulation (e.g., heat or massage) Why does electrical stimulation to the periaqueductal Emotional conditions gray area of the brainstem produce analgesia? The search Positive emotions (e.g., happiness or optimism) for an answer to this question played an important part Relaxation in major discoveries about the neurochemical bases of Rest Mental conditions pain. We will begin this section by examining some of Intense concentration or distraction these discoveries and seeing that the neurochemical Involvement and interest in life activities substances that underlie acute pain are linked to psychosocial processes. Then we will consider how Source: Based on material by Karol et al., cited in Turk, psychosocial factors are related to the experience of Meichenbaum, & Genest, 1983. chronic pain. k  k Chapter 11 / The Nature and Symptoms of Pain 299 NEUROCHEMICAL TRANSMISSION chemicals. (Endogenous means “developing from within,” AND INHIBITION OF PAIN and oid is a suffix meaning “resembling.”) Endogenous opioids and opiates (morphine and heroin) appear to The phenomenon whereby stimulation to the brainstem function in much the same way in reducing pain (Tortora produces insensitivity to pain has been given the name & Derrickson, 2012; Winters, 1985)). Many neurons in the stimulation-produced analgesia (SPA). To understand central nervous system have receptors that are sensitive how SPA occurs, we need to see how transmission to both opiates and opioids, and allow these chemicals cells are activated to send pain signals to the brain. to bind to them. Evidence now indicates that people This activation is triggered by a neurotransmitter called with chronic pain have impaired endogenous opioid substance P that is secreted by pain fibers and crosses the systems, which may partly explain why their pain gets synapse to the transmission cells (Mann & Carr, 2006; worse and why they are highly sensitive to acute pain Tortora & Derrickson, 2012). SPA occurs when another (Bruehl, McCubbin, & Harden, 1999). This impairment chemical blocks the pain fibers’ release of substance is especially strong if their parents also suffered from P. Let’s see how this happens and what this other chronic pain (Bruehl & Chung, 2006). chemical is. How Opiates and Opioids Work What Stimulating the Periaqueductal Gray Researchers have studied the action of opiates and Area Does endogenous opioids by using the drug naloxone, which Stimulation to the periaqueductal gray area starts a acts in opposition to opiates and opioids and prevents neurochemical chain reaction that seems to take the them from working as painkillers (Pagliaro & Pagliaro, course shown in Figure 11-3. The impulse travels 2012; Winters, 1985). In fact, physicians administer down the brainstem to the spinal cord, where the naloxone to counteract the effects of heroin in addicts neurotransmitter serotonin activates nerve cells called who have taken an overdose of the narcotic. In studying “inhibitory interneurons.” Impulses in these interneurons the action of opioids, researchers have examined whether then cause the release of the neurotransmitter endorphin these chemicals are involved in the phenomenon of k at the pain fibers; endorphin inhibits these fibers from SPA and found that naloxone blocks the analgesic k releasing substance P (Mann & Carr, 2006; Tortora & effects of electrical stimulation to the periaqueductal Derrickson, 2012). gray area: animals with naloxone react strongly to the Endorphin is a chemical belonging to a class of pain, but those without naloxone do not (Akil, Mayer, & opiatelike substances called endogenous opioids that Liebeskind, 1976). Furthermore, research with humans the body produces naturally; enkephalin is another of these found that injecting naloxone in patients who have undergone tooth extractions increases their pain (Levine, Gordon, & Fields, 1978). These findings indicate that endogenous opioids are involved in producing SPA. Brain The body clearly contains its own natural painkilling Periaqueductal Serotonin gray area Pain messages substances, but the ways by which they reduce pain are more complicated than they once appeared (Cannon et al., 1982; Melzack & Wall, 1982). Three issues are relevant. First, studies have found that naloxone does not always block SPA. Second, some research findings suggest that neurotransmitters may have different effects Inhibitory Transmission for momentary pain than for pain lasting for an hour or Pain interneurons Endorphin fibers Substance P cells more; most research has been with pain that lasts only seconds or minutes. Third, when morphine is given to Spinal cord control pain, tolerance to the drug occurs quickly for momentary pain but does not seem to occur for longer- lasting acute pain and for chronic severe pain, such as Figure 11-3 Illustration of the chain of activity involved that experienced by some cancer patients. These patients in SPA. Stimulation to the periaqueductal gray area of generally don’t increase their doses, even across months the brain starts a sequence of electrochemical reactions, or years of use (Melzack & Wall, 1982). Just why these eventually leading to inhibition (shown by shaded arrows) differences in tolerance occur is unclear. of the pain fibers’ release of substance P, thereby reducing Having internal pain-relieving chemicals in the pain messages from the transmission cells to the brain. body serves an adaptive function. It enables people k  k 300 Part V / Physical Symptoms: Pain and Discomfort to regulate the pain they experience to some extent associated with pain-related words, such as “excru- so that they can attend to other matters, such as ciating” and “squeezing,” showed brain activation in taking immediate action to survive serious injuries. Pain pain regions to those words but not others (Richter activates this analgesic system (Winters, 1985). But most et al., 2010). Other research found that people can of the time, high levels of endogenous opioid activity learn via classical conditioning to make specific mus- are not needed and would be maladaptive because cular responses to stimuli that had been presented with chronic analgesia would undermine the value of pain pain repeatedly, and that this association may con- as a warning signal. Perhaps because pain and emotions tribute to low back pain becoming chronic in everyday are closely linked, studies have found that psychological life (Schneider, Palomba, & Flor, 2004). stress can trigger endogenous opioid activity (Bloom, Learning also influences the way people behave Lazerson, & Hofstadter, 1985; Winters, 1985). The release when they are in pain. People in pain behave in of endogenous opioids in times of stress may help characteristic ways—they may moan, grimace, or limp, to explain how injured athletes in competition and for instance. These actions are called pain behaviors, soldiers on the battlefield continue to function with and they can be classified into four types (Turk, Wack, & little or no perception of pain. The connection between Kerns, 1985): stress, coping, and opioid activity points up the interplay 1. Facial or audible expression of distress, as when people clench between biological and psychosocial factors in people’s their teeth, moan, or grimace. experience of pain. (Go to.) 2. Distorted ambulation or posture, such as moving in a guarded or protective fashion, stooping while walking, or rubbing PERSONAL AND SOCIAL EXPERIENCES or holding the painful area. AND PAIN 3. Negative affect, such as being irritable. 4. Avoidance of activity, as when people lie down frequently Imagine this scene: little Stevie is a year old and is in the during the day, stay home from work, or refrain from pediatrician’s office to receive a standard immunization motor or strenuous behavior. shot, as he has done before. As the physician approaches k with the needle, Stevie starts to cry and tries to kick the Pain behaviors are a part of the sick role and are k doctor. He is reacting in anticipation of pain—something often strengthened or maintained by reinforcement in he learned through classical conditioning when he had operant conditioning, without the person’s awareness (Hölzl, received vaccinations before. Kleinböhl, & Huse, 2005; Turk, Wilson, & Swanson, 2012). Two findings are important about the conditioning of Learning and Pain pain behaviors. First, researchers demonstrated that facial displays of pain can become more pronounced We learn to associate pain with antecedent cues and or less so, depending on which is reinforced, and that its consequences, especially if the pain is severe and as these people’s pain behaviors changed, their ratings repeated, as it usually is with chronic pain (Martin, of painful stimuli changed in the same direction—for Milech, & Nathan, 1993). Many individuals who suffer instance, the stronger the facial display, the higher the from migraine headaches, for example, often can tell pain ratings (Kunz, Rainville, & Lautenbacher, 2011). when headaches are on the way because they experience Second, when pain persists and becomes chronic, pain symptoms, such as dizziness, that precede the pain. behaviors often become a stable part of the person’s These symptoms become conditioned stimuli that tend habits and lifestyle: a study found that pain behaviors to produce distress, a conditioned response, and may of people with chronic back pain were stable over heighten the perception of pain when it arrives. time, even when pain severity and fear of movement Words or stimuli that relate to the pain we have fluctuated (Martel, Thibault, & Sullivan, 2010). People experienced can also become conditioned stimuli and with entrenched patterns of pain behavior usually feel produce conditioned responses. A study of people who powerless to change. do and do not have migraine headaches measured their How are pain behaviors reinforced in everyday physiological arousal in response to pain-related words, life? Although being sick or in pain is unpleasant, it such as “throbbing” and “stabbing” (Jamner & Tursky, sometimes has benefits, or “secondary gains.” Someone 1987). Migraine sufferers displayed much stronger phys- who is in pain may be relieved of certain chores around iological reactions to these words—especially the words the house or of going to work, for instance. Also, when a that described their own experience with pain—than person has a painful condition that flares up in certain those without migraines did. Similarly, people without circumstances, such as when lifting heavy objects, he or chronic pain who were asked to imagine situations she may begin to avoid these activities. In both of these k  k Chapter 11 / The Nature and Symptoms of Pain 301 HIGHLIGHT Placebos and Pain You have probably heard of physicians Why do placebos reduce pain? One reason is that prescribing a medicine that actually consisted of “sugar they sometimes reduce stress, which reduces the pain pills” when they could not find a physical cause for a experience (Aslaksen & Flaten, 2008). Another reason patient’s complaints or did not know of any medication is that psychological processes trigger the release of that would help. You may also have heard that this endogenous opioids in the person’s body, thereby treatment sometimes works—the patient claims the inhibiting the transmission of pain signals. Two of these symptoms are reduced. An inert substance or procedure triggering processes are expectancies and classical conditioning that produces an effect is called a placebo. Studies have (Klinger et al., 2014; Stewart-Williams, 2004). These are shown that placebos are often effective in treating a the same processes we discussed in Chapter 7 that lead variety of ailments, including asthma, nausea, and pain to dependence on substances, such as drugs and alcohol. (Häuser et al., 2011; Hróbjartsson & Gøtzsche, 2010). In both processes, people acquire from past experience a And an effective placebo need not be a substance: an connection between active treatments and their effects, experiment found that of patients who got sham surgery such as reduced pain, so that something resembling for arthritis of the knee or real surgery, nearly 40% of each an active treatment—the placebo—can lead to the group claimed to have less pain and better movement effect. Earlier in the current chapter, we saw the role of (Moseley et al., 2002). endogenous opioids in stimulation-produced analgesia Placebos do not always work in treating pain, but (SPA); this role is important in placebos, too. Research they produce substantial relief in about half as many with double blind procedures has shown that placebos patients as do real drugs, such as aspirin or morphine do, in fact, elicit the body’s production of endogenous (Melzack & Wall, 1982; Rehm & Nayak, 2004). The effect opioids and that people who receive naloxone to block of placebos depends on the patient’s belief that they will the transmission of pain signals report more discomfort work—for instance, they are more effective: than those who do not get naloxone with pain from k k muscle ischemia and actual tooth extractions (Benedetti With large doses—such as more capsules or larger et al., 2003; Fields & Levine, 1984; Johansen, Brox, & ones—than with smaller doses. Flaten, 2003). When injected than when taken orally. The effects of placebos are fascinating and impor- When the practitioner indicates explicitly and strongly tant, but they also present major ethical dilemmas for that they will work. practitioners. Is it appropriate to use placebo drugs or procedures to treat symptoms and illnesses—and if so, Unfortunately, however, the effectiveness of placebos in when and under what circumstances? treating pain tends to decline with repeated use. situations, pain behavior is reinforced if the person does rehabilitation programs (Trabin, Rader, & Cummings, not like these activities in the first place: getting out 1987). of doing them is rewarding. Another way pain behavior and other sick-role behaviors may be reinforced is if the Social Processes and Pain person receives disability payments. Studies of injured or ill patients who differ in the financial compensation they People who suffer with pain generally receive attention, receive have found that those with greater compensation care, and affection from family and friends, which tend to remain hospitalized and miss work longer, report can provide social reinforcement for pain behavior. more chronic pain, and show less success from pain Researchers have demonstrated this relationship with treatments (Chapman, 1991; Newton-John & McDonald, both child and adult patients. Karen Gil and her 2012; Rohling, Binder, & Langhinrichsen-Rohling, 1995). colleagues (1988) videotaped parents’ reactions to the In some cases, people who take longer to recover may be pain behavior of their children who had a chronic malingering, but others may just be willing to take more skin disorder with severe itching that should not be time and prevent a relapse. Still, many pain patients scratched because it can cause peeling and infection. who receive disability compensation show substantial An analysis revealed that the children’s scratching emotional and behavioral improvements from pain increased, rather than decreased, when parents paid k  k 302 Part V / Physical Symptoms: Pain and Discomfort attention to scratching, and paying attention to the social processes in the pain patient’s family system can children when they were not scratching seemed to gradually and insidiously increase his or her dependency reduce their scratching behavior. Parents of children and physical deterioration, such as through muscle with pain conditions who distract their children from the atrophy, and decrease self-efficacy and self-esteem. Self- symptoms decrease pain behavior, and their children efficacy is important because people who believe they report feeling better than others who receive attention cannot control their pain very well experience more pain for their symptoms (Walker et al., 2006). Children whose and use more medication than those who believe they parents are critical or overly protective of their pain can control it (Gatchel et al., 2007; Turk, Wilson, & tend to become increasingly disabled, particularly if they Swanson, 2012). have high levels of emotional distress (Claar, Simons, & Logan, 2008). Studies have assessed how patients’ pain behaviors Gender, Sociocultural Factors, and Pain relate to their receiving social rewards, such as being able to avoid disliked social activities or getting solicitous care Studies have found gender and sociocultural differences from a spouse—that is, high levels of help and attention in the experience of pain. Men and women are similar (Newton-John, 2002; Raichle, Romano, & Jensen, 2011). in their pain thresholds—that is, the stimulus intensity at Receiving higher levels of social reward for sick-role which they start to feel pain—but differ in their reactions behavior and less encouragement for well behavior to pain. For instance, women give higher ratings than are associated with patients reporting more pain and men for pain in cold-pressor tests, and some evidence showing more disability and less activity, such as in suggests this may result in part from different effects of visiting friends or going shopping. In one study, patients endogenous opioids (al’Absi et al., 2004; Racine et al., with chronic pain were interviewed about their spouses’ 2012). What about the types of pain conditions men solicitousness regarding their pain behavior (Block, and women experience in everyday life? In the United Kremer, & Gaylor, 1980). The interviews occurred in States, the prevalence rate of severe headache is far meetings in which the patients were aware of being higher for women than men, and women have higher observed through a one-way mirror and who was rates of low back pain, neck pain, and joint pain k (NCHS, 2014). Women report more than men that pain k observing: their spouse or a hospital employee. The degree of pain the patients described depended on interfered with their daily activities (Lester, Lefebvre, & whether the spouse or the employee was observing and Keefe, 1994). whether the patient thought the spouse was solicitous. Research has compared pain in people from different Patients who felt their spouses were solicitous reported socioeconomic and ethnic groups. In the United States, more pain when their spouses watched than when the sensitivity to laboratory-induced pain was higher among employee did, but those who felt their spouses were Asian Americans than Whites, who showed higher pain not solicitous reported less pain when their spouses sensitivity than African and Hispanic American individu- watched than when the employee did. Spouses very often als (Lu, Zeltzer, & Tsao, 2013). In everyday life, people in overestimate the pain that patients feel, and those who a variety of nations in lower socioeconomic classes expe- do are less supportive of patients’ engaging in everyday rience more pain than those in higher classes (Poleshuck activities (Martire et al., 2006). & Green, 2008). Surveys of adults in different countries Findings on parents’ and spouses’ reactions to who suffer from chronic low back pain revealed greater chronic pain behavior and the social climate within work and social impairments among Americans, followed the family system illustrate how each family member’s by Italians and New Zealanders, and then by Japanese, behavior impacts on the behavior of the others (Kerns & Colombian, and Mexican individuals (Sanders et al., Weiss, 1994; Romano, Turner, & Jensen, 1997). When 1992). In the United States, prevalence rates of migraine families lack cohesion or the members are highly headache and pain in the lower back, neck, and joints are solicitous to pain behavior without encouraging the much lower for Asian Americans than for Whites, Blacks, patient to become active, they tend to promote sick-role and Hispanic Americans (NCHS, 2014). After dental behavior. These conditions can lead to a vicious circle: surgery, Blacks reported more acute pain than people of solicitousness may elicit more pain behavior, which leads European, Asian, or Hispanic backgrounds, and women to more solicitousness, and so on. Showing care and in each group reported more pain than men (Faucett, concern when people are in pain is, of course, important Gordon, & Levine, 1994). But other studies have found and constructive—for instance, receiving emotional little or no ethnic pain differences, and knowing of actual support when in pain reduces the person’s stress and differences is of little value for a practitioner treating pain intensity (Roberts, Klatzkin, & Mechlin, 2015). But individual people (Korol & Craig, 2001). k  k Chapter 11 / The Nature and Symptoms of Pain 303 pain are determined more by what they expect than by what they feel. Does Emotion Affect Pain? Positive emotions, such as laughter, appear to reduce pain (Finan & Garland, 2015). But the role of negative emotions has received more research attention. Most people with chronic pain experience high levels of depression, anxiety, or anger (Gatchel et al, 2007), and high levels of these emotions have been linked to high levels of subsequent pain and disability (Burns et al., 2015; Castillo et al., 2013; Lerman et al., 2015). A study of patients with depressive or anxiety disorders and chronic pain in at least one body area found that the chances of continued depression or anxiety 2 years later increased with the severity of the pain, the number of affected body areas, and the duration of the pain (Gerrits et al., 2012). Do negative emotions affect pain? In the case of headache, investigations using self-report methods have found a sequence: migraine and muscle-contraction headaches tend to occur after periods of heightened Age Fotostock America, Inc. stress and that this link is pronounced for depressed individuals (Janke, Holroyd, & Romanek, 2004; Nash & Thebarge, 2006; Wittrock & Myers, 1998). Has research shown that emotion can cause headaches? k k Convincing evidence that stress can cause headaches comes from a study with adults who suffered from either chronic headache or only occasional headaches (Gannon et al., 1987). Before testing a sub- Pain is an important factor in dentistry: it motivates patients ject, a researcher attached sensors to the person’s body to seek treatment, but the discomfort during visits makes to take physiological measurements, such as of heart them feel uneasy about going in the