Chronic pain patients often have psychiatric disorders that negatively influence their responses to treatment. Also, many of them have dysfunctional beliefs and coping strategies, even if they do not meet DSM-5 criteria for a psychiatric disorder. Physiatrists should have a low threshold for referring both groups of patients for mental health services. This article describes psychiatric disorders that are highly prevalent among pain patients and also describes psychological processes that contribute to poor coping by the patients. Finally, it discusses factors that a physiatrist should consider in deciding whether to refer patients to psychiatrists versus psychologists.
Key points
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Several psychiatric disorders are so common among chronic pain patients that physiatrists should be alert to them. They include major depressive disorder, dysthymia, panic disorder, posttraumatic stress disorder, and various substance use disorders.
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A high proportion of chronic pain patients have dysfunctional belief systems about their conditions and/or dysfunctional coping strategies to deal with their conditions. These beliefs and coping strategies can occur in the absence of a diagnosable psychiatric condition and can have significant negative impacts on the patients’ response to treatment.
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Physiatrists should consider several factors when they decide whether to refer a pain patient to a psychiatrist or a psychologist. In general, though, an initial referral to a psychiatrist is usually the best strategy.
Introduction
Physiatrists who treat patients with chronic pain frequently request assistance from mental health practitioners. The 2 types of professionals who typically evaluate these patients are psychiatrists and clinical psychologists. The present article describes the perspectives taken by these 2 professional groups and offers recommendations about when to refer to a psychiatrist versus a psychologist.
Introduction
Physiatrists who treat patients with chronic pain frequently request assistance from mental health practitioners. The 2 types of professionals who typically evaluate these patients are psychiatrists and clinical psychologists. The present article describes the perspectives taken by these 2 professional groups and offers recommendations about when to refer to a psychiatrist versus a psychologist.
The psychiatric perspective
Any discussion of psychiatric disorders in patients with chronic pain is haunted by the concept of psychogenic pain. One is drawn to this concept because it fills the gaps left when the attempts fail to explain clinical pain exclusively in terms of tissue pathologic abnormality. In fact, psychogenic pain was codified into the pain disorder diagnosis in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The diagnosis presumes that some pain conditions are solely or predominantly explained by psychological factors rather than medical conditions. Psychogenic pain, however, is an empty concept. Positive criteria for the identification of psychogenic pain, mechanisms for the production of psychogenic pain, and specific therapies for psychogenic pain are lacking. Psychiatric diagnosis of many disorders, such as depression, can be helpful to the clinician and the patient by pointing to specific effective therapies. However, the diagnosis of psychogenic pain too often only serves to stigmatize further the patient who experiences chronic pain.
A notable and welcome change from DSM-IV to DSM-5 is the elimination of the pain disorder diagnosis. The rationale for its removal was given in the introductory section to the chapter, “Somatic Symptoms and Related Disorder,” in DSM-5: “The reliability of determining that a somatic symptom is medially unexplained is limited, and grounding a diagnosis on the absence of an explanation is problematic and reinforces mind-body dualism” (American Psychiatric Association, 2013, p. 309).
Epidemiologic evidence supports the use of inclusive rather than exclusive models of psychiatric diagnoses in medical settings that allows for the presence of both medical disease and mental disorders. Medical illness in no way excludes the possibility of a clinically important psychiatric illness. Medically ill patients are, in fact, much more likely to have psychiatric illness than patients without medical illness. Psychiatric illness in no way precludes the possibility of a clinically important medical illness. Psychiatric illness is, in fact, associated with health behaviors and physiologic changes known to promote medical illness.
In the discussion that follows, psychiatric disorders as defined in DSM-5 are used as an organizing strategy. It is important to note, however, that the categorical model of mental disorder favored by psychiatrists and used in DSM-5 can imply more discontinuity between those with and those without a mental disorder than is actually the case. For example, it is common for patients with chronic pain to partially meet criteria for several mental disorders. Therefore, it is sometimes useful to think of these disorders as dimensions rather than categories. The DSM-5 nevertheless provides a well-recognized and systematic template for the discussion of psychiatric disorders in patients with chronic pain.
When asked to evaluate patients at the authors’ Center for Pain Relief, they typically consider the following issues: depression, anxiety, trauma and abuse history, posttraumatic stress disorder (PTSD), and substance use disorders. The authors do not usually use a structured interview for psychiatric diagnosis, but some brief, self-administered questionnaires are routinely given to the patients at every visit to screen for major psychiatric symptoms and for outcome tracking in a nonresearch clinical setting. These evaluations include the 9-item Patient Health Questionnaire, the Generalized Anxiety Disorder 7-item scale, and a 4-item Primary Care PTSD Screen.
Depression
One must begin by distinguishing between depressed mood and the clinical syndrome of major depression. It is important to note, especially when working with chronic pain patients, that depressed mood or dysphoria is not necessary for the diagnosis of major depression. Anhedonia, the inability to enjoy activities or experience pleasure, is an adequate substitute. It is common for patients with chronic pain to deny dysphoria but to acknowledge that enjoyment of all activities has ceased, even those without obvious relation to their pain problem (eg, watching television for a patient with low back pain).
The DSM-5 criteria for major depressive episode include both psychological symptoms (worthlessness or guilt, thoughts of death or dying) and somatic symptoms (insomnia or hypersomnia, change in appetite, fatigue, trouble concentrating, psychomotor agitation, or retardation). The presence of 5 or more symptoms is required for diagnosis of a major depressive episode. It is important to note that somatic symptoms count toward a diagnosis of major depression unless they are due to “clearly and fully attributable to a general medical condition” or medication (American Psychiatric Association, 2013, p. 164). The poor sleep, poor concentration, and lack of enjoyment often experienced by patients with chronic pain are frequently attributed to pain rather than to depression. However, because they are not a direct physiologic effect of pain, these symptoms should count toward a diagnosis of depression. In fact, studies of depression in medically ill populations have generally found greater sensitivity and reliability with “inclusive models” of depression diagnosis that accept all symptoms as relevant to the diagnosis than with models that try to identify the cause of each symptom.
Patients with chronic pain often dismiss a depression diagnosis, stating that their depression is a reaction to their pain problem. Psychiatry has long debated the value of distinguishing a “reactive” form of depression caused by adverse life events and an endogenous form of depression caused by biological and genetic factors. Life events are important in many depressive episodes, although they play a less important role in recurrent and very severe or melancholic or psychotic depressions. Previously in DSM-IV, the only life event that excludes someone who otherwise qualifies for a major depression diagnosis is bereavement. This exclusion is eliminated in DSM-5 for several reasons, one of which is that bereavement-related depression responds to the same treatments as non-bereavement-related depression. Determining whether a depression is a “reasonable response” to life’s stress may be very important to patients seeking to decrease the stigma of a depression diagnosis, and it has been of interest to pain investigators. It is not, however, important in deciding whether treatment is necessary and appropriate. Indeed, in assessment there is no clarity to be gained from debating whether the depression caused the pain or the pain caused the depression. If patients meet the criteria outlined earlier, they can likely benefit from appropriate treatment.
When considering the diagnosis of depression in patients with chronic pain, important alternatives include bipolar disorder, substance-induced mood disorder, and dysthymic disorder. Patients with bipolar disorder have extended periods of abnormally elevated or irritable, as well as abnormally depressed, mood. These periods of elevated mood need to last several, continuous days (4 days for a hypomanic episode, 1 week for a manic episode) and include features such as inflated self-esteem, decreased need for sleep, increased goal-directed activity, and racing thoughts. A history of manic or hypomanic episodes predicts an atypical response to antidepressant medication and increases the risk of antidepressant-induced mania. Bipolar disorder is less common (12-month prevalence in the general population 2.6 vs 6.7%) than unipolar depression, but it is important to recognize because it requires a different treatment approach.
Substance-induced mood disorders can also occur in those with pain. Patients with chronic pain may be taking medications such as steroids, dopamine-blocking agents (including antiemetics), or sedatives (including “muscle relaxants”) that produce a depressive syndrome. Patients’ current medication lists should be scrutinized for potential depressogenic medications. For patients with a pure substance-induced mood disorder, symptoms can persist for up to a month after discontinuation of the substance but will eventually resolve. It should be noted that some patients with an underlying mood disorder “self-medicate” with other substances (drugs, alcohol); hence, establishing the temporal relationship (as much as possible) between the onset of mood symptoms and substance abuse is important for diagnosis and treatment planning.
Dysthymic disorder is a chronic form of depression lasting 2 years or longer. Individuals with dysthymia are at high risk to develop major depression as well. This combined syndrome has often been called “double depression.” It is important to note that dysthymia is frequently invisible in medical settings, often dismissed as “just the way that patient is.” Dysthymia has been shown to respond to many antidepressants, including the selective serotonin reuptake inhibitors. Treatment of double depression can be particularly challenging because of treatment resistance and concurrent personality disorders. Psychiatric consultation may be useful when any of these disorders is suspected.
Twelve-month prevalence rates for major depression and dysthymia in the general population are 6.7% and 1.5%, respectively. Among individuals endorsing one or more chronic pain conditions in the general population (back/neck, arthritis, migraine/chronic headaches), 12-month rates are generally higher, 10% to 30%. Prevalence rates of depression among patients in pain clinics have varied widely depending on the method of assessment and the population assessed. Rates as low as 10% and as high as 100% have been reported. The reason for the wide variability may be attributable to several factors, including the methods used to diagnose depression (eg, interview, self-report instruments), the criteria used (eg, cutoff scores on self-report instruments), the set of disorders included in the diagnosis of depression (eg, presence of depressive symptoms, major depression), and referral bias (eg, higher reported prevalence of depression in studies in psychiatry clinics compared with rehabilitation clinics). Overall, chronic pain increases depression risk by 2-fold to 5-fold.
Studies of primary care populations have revealed several factors that seem to increase the likelihood of depression in patients with chronic pain. Patients with 2 or more pain complaints were much more likely to be depressed than those with a single pain complaint. Number of pain conditions reported was a better predictor of major depression than pain severity or pain persistence. Von Korff and colleagues developed a 4-level scale for grading chronic pain severity based on pain disability and pain intensity: (1) low disability and low intensity, (2) low disability and high intensity, (3) high disability-moderately limiting, and (4) high disability-severely limiting. Depression, use of opioid analgesics, and doctor visits all increased as chronic pain grade increased.
Patients with chronic pain often feel they are battling to have their suffering recognized as real. They resist a depression diagnosis if they see it as a way to dismiss their suffering. Even if clinicians are sensitive to these issues, they must recognize that legal proceedings, insurance companies, and workers’ compensation boards can look on a depression diagnosis with prejudice. Traditional and industrial societies seem to hold individuals less responsible for somatic symptoms than for psychological symptoms. This difference may be especially prominent in modern Western biomedicine, whereby symptom complexes are validated or invalidated through their correspondence with objective disease criteria. Pain is a more acceptable reason for disability than depression in many cultures. Therefore, cultural incentives exist for translation of depression into pain. Because depressed patients have many physical symptoms, these can become the focus of clinical communication and concern. Giving patients with chronic pain permission to talk of distress in the clinical setting using nonsomatic terms can facilitate treatment as long as they do not feel that somatic elements of their problem are being neglected or discounted. The authors try to validate depression as an understandable response to a chronic pain problem.
Anxiety Disorders
It is not unusual for patients with symptoms of pain to be anxious and worried; however, this is not synonymous with a psychiatric diagnosis of an anxiety disorder. When patients with chronic pain do suffer from an anxiety disorder, it is rare that this is their sole psychiatric diagnosis. Most patients with pain and chronic anxiety also meet criteria for either major depression or dysthymia. In these cases, treatment should be directed toward the mood disorder. With successful treatment of the mood disorder, the anxiety should be relieved as well. Benzodiazepines are best avoided because of their association with tolerance, dependence, and withdrawal. Prolonged use may promote inactivity and cognitive impairment.
Panic disorder
Panic disorder is a common, disabling psychiatric illness associated with high medical service utilization and multiple medically unexplained symptoms. In the pain clinic setting, panic disorder should be considered especially in patients with chest pain, abdominal pain, or headaches. The diagnosis of panic disorder requires that recurrent, unexpected panic attacks be followed by at least a month of worry about having another panic attack, about the implications or consequences of the panic attacks, or behavioral changes related to the attacks. A panic attack is defined as a discrete period of intense fear or discomfort in which 4 or more symptoms are present. As with major depression, DSM-5 criteria include symptoms that are somatic (increased heart rate, palpitations, sweating, shortness of breath, chest pain, trembling, dizziness, chills or hot flushes, nausea, feeling of choking, paresthesias) and psychological (fear of dying, fear of losing control, or going crazy). These attacks should not be the direct physiologic consequence of a substance or other medical condition. The panic attacks should not be better accounted for by another mental disorder, such as PTSD (described later) or obsessive-compulsive disorder. At least 2 unexpected attacks are required for the diagnosis, although most patients have more.
One of the most common problems with panic disorder is the fear of undiagnosed, life-threatening illness. Patients with panic disorder can receive extensive medical testing and treatment of their somatic symptoms before the diagnosis of panic disorder is made and appropriate treatment is initiated. Lifetime prevalence of panic disorder throughout the world is estimated to be 1.5% to 4.7%. One-year prevalence rates are from 1% to 2.7%. Panic disorder is 2 to 3 times more common in women than in men. Age of onset is variable, but most cases typically occur between late adolescence and the mid-30s. Of all common mental disorders in the primary care setting, panic disorder is most likely to produce moderate to severe occupational dysfunction and physical disability. It is also associated with the greatest number of disability days in the past month.
Panic disorder is commonly associated with agoraphobia, or fear of public places. Patients with panic disorder learn to fear places where escape might be difficult or help may not be available in case they have an attack. Major depression is another common comorbidity in patients suffering from panic disorder. The differential diagnosis of patients presenting with panic symptoms in the medical setting includes thyroid, parathyroid, adrenal, and vestibular dysfunction, seizure disorders, cardiac arrhythmias, and drug intoxication or withdrawal. Patients with panic disorder typically present in the medical setting with cardiologic, gastrointestinal, or neurologic complaints.
Chest pain is one of the most common complaints presented to primary care physicians, but a specific medical cause is identified in only 10% to 20% of cases. From 43% to 61% of patients with normal coronary arteries at angiography and 16% to 25% of patients presenting to emergency rooms with chest pain have panic disorder. Several of these patients eventually receive the diagnoses of vasospastic angina, costochondritis, esophageal dysmotility, or mitral valve prolapse. High rates of psychiatric disorders have been found in some of these groups as well. Many of these patients remain symptomatic and disabled 1 year later despite reassurance concerning coronary artery disease.
Approximately 11% of primary care patients present with the complaint of abdominal pain to their physician each year. Less than a one-fourth of these symptoms are associated with a definite physical diagnosis in the following year. Among the most common reasons for abdominal pain is irritable bowel syndrome. It is estimated that irritable bowel syndrome accounts for 20% to 52% of all referrals to gastroenterologists. Various studies have found that 54% to 74% of these patients with irritable bowel syndrome have associated psychiatric disorders. Patients with irritable bowel syndrome have much higher current (28 vs 3%) and lifetime (41 vs 25%) rates of panic disorder than a comparison group with inflammatory bowel disease, suggesting that the psychiatric disorder was not simply a reaction to the abdominal distress. Other studies have suggested that migraine headache is most strongly associated with panic attacks. Often anxiety symptoms precede the onset of the headaches, whereas depressive symptoms often have their onset after the headaches. Some authors have suggested that people with panic attacks have a common predisposition to headaches (especially migraines and chronic daily headache), anxiety disorders, and major depression.
Posttraumatic Stress Disorder
Previously classified as an anxiety disorder in DSM-IV, PTSD is now in the new category of trauma-related and stress-related disorders in DSM-5. Following direct or indirect exposure to an extreme traumatic event, some individuals develop a syndrome that includes re-experiencing the event, avoidance of stimuli associated with the event, persistent heightened arousal, and negative cognitions or emotion. PTSD was originally described following exposure to military combat, but it is now recognized that it occurs following sexual or physical assault, natural disasters, accidents, life-threatening illnesses, and other events that induce feelings of intense fear, hopelessness, or horror. Persons may develop the disorder after experiencing or just witnessing these events. DSM-5 diagnostic criteria require that the person either experienced or witnessed an event that involved actual or threatened death, serious injury, or threat to the physical integrity of the self or others. Posttraumatic symptoms must last more than 1 month. The event can be re-experienced in the form of recurrent nightmares, flashbacks, or intense psychological distress or physical reactivity in response to internal or external cues resembling the event. Persistent avoidance can present as avoiding thoughts or memories about the event, or avoiding people, places, or situations that arouse memories of the event. Two or more symptoms of negative alterations in cognitions and affect (inability to recall important aspects of the trauma, exaggerated negative beliefs about oneself or others, distorted cognitions about the cause or consequences of the trauma, persistent negative emotional state, diminished interest in activities, a feeling of detachment from others, and inability to experience positive emotions) and 2 or more symptoms of increased arousal (eg, disturbed sleep, irritability, self-destructive behavior, hypervigilance, increased startle response, difficulty concentrating) should also be present.
Up to 80% of Vietnam veterans with PTSD report chronic pain in limbs, back, torso, or head. Increased physical symptoms, including muscle aches and back pain, are also more common in Gulf War veterans with PTSD than in those without PTSD. The 12-month prevalence of PTSD in the general population is 3.5%. The prevalence of PTSD in medical populations has been shown to be quite high. Averaging the prevalence rates of PTSD across several studies reveals that following motor vehicle accidents sufficiently severe to require medical attention, 29.5% of patients met the criteria for PTSD. For more than one-half of these patients, the symptoms resolved within 6 months. In one study, 15% of patients seeking treatment of idiopathic facial pain were found to have PTSD. In another study, 21% of patients with fibromyalgia were found to have PTSD. Case reports have associated reflex sympathetic dystrophy (complex regional pain syndrome) with PTSD. Other studies suggest that 50% to 100% of patients presenting at pain treatment centers meet the diagnostic criteria for PTSD. Pain patients with PTSD have been shown to have more pain and affective distress than those without PTSD, so it is not surprising that PTSD rates among patients with pain increase in more specialized treatment settings.
The relationship between pain and PTSD is multifaceted. Pain and PTSD may both result from a traumatic event. Sometimes acute pain can constitute the traumatic event, such as in a case of traumatic eye enucleation, and in cases of implantable cardioverter defibrillator discharges. PTSD also appears to permit induction of an opioid-mediated, stress-induced analgesia. PTSD-related stimuli can result in a naloxone-reversible decreased sensitivity to noxious stimuli in affected individuals.
The relation between childhood abuse and chronic pain has received plenty of attention in recent years. Multiple studies have demonstrated higher rates of childhood maltreatment in patients with chronic pain than in comparison groups. They have also shown poorer coping among abused patients with pain. However, the relationship between childhood psychological trauma and adult somatic symptoms is complex. PTSD, dissociation, somatization, and affect dysregulation represent a spectrum of adaptations to trauma. They may occur together or separately. The best way to incorporate information about childhood maltreatment into the treatment of the adult patient with chronic pain is as yet unclear. It may signal to caregivers the potential challenges in establishing a therapeutic alliance. It may also mean that additional psychotherapeutic interventions are necessary beyond the coaching of pain management skills. However, chronic pain treatment trials have not yet grouped patients by trauma history or attempted treatment matching.
Substance Use Disorders
DSM-5 no longer distinguishes between substance dependence and substance abuse, as did DSM-IV. The essential feature of any substance use disorder is continued use of a substance despite a cluster of cognitive, behavioral, and physiologic problems. It is characterized by impaired control, social impairment, risky use, and the development of tolerance and withdrawal.
Diagnosis of substance use disorders in patients with chronic pain is controversial, because it is difficult to achieve consensus on what constitutes a maladaptive pattern of substance use, especially with regard to prescription opioids. Traditionally, opioids have been considered appropriate for terminal cancer pain, with tolerance, dependence, and dose escalation limited in their importance by the impending death of the patient. However, they have been considered problematic for the chronic noncancer patient with pain whose long-term function is an essential issue. A large percentage of patients referred to multidisciplinary pain centers report taking opioids at the time of assessment. Following treatment, most of these patients report significantly reduced pain concurrent with elimination of opioid medication. Portenoy and others have argued forcefully that chronic opioid therapy can be appropriate and beneficial in some patients with chronic noncancer pain. One of the current, unanswered questions is what factors characterize those patients who are likely to benefit from long-term opioids without problems of addiction, tolerance, or increased disability. To date, there have been no long-term, double-blind studies that help to select the group for whom long-term opioids are beneficial. Nevertheless, in recent years, there has been a marked increase in the use of opioids for chronic noncancer pain. Several recent studies have found that individuals with underlying depressive, anxiety, or substance use disorders are more likely than those without these disorders to receive opioids for noncancer pain. Hence, screening for and treating these disorders in individuals on, or being considered for, opioid therapy are important.
The lifetime and 12-month prevalences of substance use disorders in the general population are 14.6% and 3.8%, respectively. Prevalence rates for substance abuse in patients with chronic pain are variable because of differences in definitions used and populations assessed. Overall, persistent pain seems to increase the risk of problem substance use by 2-fold to 5-fold. Studies completed to date suggest that substance use disorders occur in a minority of chronic pain patients on opioids. They do not answer the more difficult question of whether opioids are, on balance, beneficial treatment for these patients in terms of reduction and improvement of function.
Because small amounts of alcohol use can retard response to antidepressant medication, it is important to inquire about alcohol use that may not otherwise meet criteria for abuse in patients who are candidates for antidepressant medication. The authors encourage patients they place on antidepressant medication to limit alcohol use to 1 or 2 drinks per week. Significant others and other third parties can provide useful information about substance use. The authors also encourage the use of urine toxicology screens in any patients with histories of substance use. Often this is the only way to be sure about the cause of a patient’s altered mental status, such as affective lability, cognitive impairment, and treatment nonresponse.
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