Chronic Pain and Depression: Sorting Out Types of Mood Disorders
Depression is a common complaint of the patient suffering with chronic pain. And pain is a common complaint of patients with mood disorders and anxiety. The challenge for the practicing physician is sorting out the psychiatric syndromes from the underlying pain triggers. This requires a comprehensive evaluation of the underlying depression. Typically, however, the patient with chronic pain is “expected to be depressed” and multidisciplinary pain management simply treats the patient with a little bit of everything: antidepressants and cognitive-behavioral psychotherapy. Unfortunately, in this scenario the roles of psychiatrists (and the patient) are often misunderstood. This article will explore the importance of differentiating types of depression in the diagnosis and management of comorbid pain and depression, and presents case examples.
Depression and Chronic Pain: The Chicken or the Egg?
As noted, physical symptoms are common in patients suffering from major depression. Approximately 60% of patients with depression report pain symptoms at diagnosis.1 The reverse trajectory is also true, and in many conditions the relationship is bidirectional. Chronic pain, from a long-term medical condition, doubles the incidence of depression. One-third to more than 50% of patients presenting to chronic pain clinics have a current major depression.2,3 Depression in patients with chronic pain is associated with greater pain intensity, more pain persistence, and greater interference from pain including more pain behaviors observed by others. Pain severity, pain-related disability, and health-related quality of life were significantly worse in patients with chronic musculoskeletal pain and comorbid depression (Figure 1).4 Depression is a better predictor of disability than pain intensity and duration.
Moreover, patients suffering from chronic pain syndromes report increased rates of suicidal ideation, suicide attempts, and suicide completion. Although other psychosocial variables play a role, depression is the most consistent and strongest predictor of suicidal ideation and behaviors in patients with chronic pain.5
Lastly, depression in patients with chronic pain is more resistant to treatment.6 Pain often subsides with improvement in depressive symptoms. Because pain has a proven effect on the response of depression to treatment, recognizing and optimizing the management of comorbid pain that commonly coexists with depression may be important in enhancing depression response and remission rates (Table 1).5 In addition to having greater efficacy for the treatment of neuropathic pain, serotonin norepinephrine reuptake inhibitors and tricyclic antidepressants are associated with faster rates of improvement in depressive symptoms and lower rates of relapse of major depressive disorder.7
Case Formulation: The Differential Diagnosis of Depression
Patients with chronic pain are referred to a psychiatrist when their chief complaint is refractory to conventional pain management, disproportionate to objective findings, or accompanied by distress intense enough to suggest depression. In some way, the depression is understandable given that the patient is long suffering with a chronic pain syndrome. However, the search for the actual cause of depression must now extend to the domain of personal consciousness.8 This realm contains not only the diseases of the brain (cerebral faculties) but also the disruptions of the motivational rhythms of behavior, the psychological constitution of the individual, and the personal chronicle of desires and life encounters.
All mental disorders, even those in patients with chronic pain, are expressions of life under altered circumstances that affect characteristic mental capacities and generate particular expressions.9,10 Four perspectives (diseases, behaviors, dimensions, life stories) represent distinct classes of disorders that each have a common essence and logical implication for causation and treatment.11,12 In this approach to patient care, diseases are what people have; behaviors are what people do; dimensions are what people are; and life stories are what people encounter (Table 2). The formulation of a patient with chronic pain experiencing depression should address the contribution from any or all perspectives to the overall presentation and inform the design of a treatment plan that can address each element of the patient’s suffering.
Diseases of the brain manifest psychologically. Abnormalities in the structures or functions of brain-based faculties such as consciousness, cognition, and affect produce mental diseases (eg, delirium, dementia, panic disorder, and major depression). However, the patient may describe deficits in these faculties with difficulty and rely on somatic symptoms (eg, pain) as incomplete proxies. The physical symptoms occur because the brain is malfunctioning and suggesting pathology in the body. The unifying feature of diseases is the presence of a broken part causing pathology.13,14 The pathology causes characteristic signs and symptoms typically manifested by the affliction.10 Finding a cure may repair the broken part, prevent the initial damage from progressing, or accommodate the pathology through secondary compensatory systems.
A 62-year-old man presents with a 4-year history of chronic pain and depression. Originally, he experienced intermittent neck pain. He was prescribed ibuprofen 800 mg by mouth every 6 hours and hydrocodone/acetaminophen 5 mg/325 mg twice by mouth every 6 hours and told to rest. He benefited from physical therapy, aerobic conditioning, and structured classes in yoga. However, his episodes of pain became more chronic and the pain more widespread throughout his body. His function deteriorated and he eventually became disabled, taking early retirement. His mood was depressed and he believed his mood would improve if his pain was adequately treated and he could return to work. He also noted a lack of self-confidence in his abilities to be successful, inability to experience pleasure, a sense of hopelessness about his future, and frequent thoughts of wanting to die as a means of gaining relief from his suffering.