Treatment-resistant somatoform disorders are chronic (duration >1 year), can cause significant functional impairment, and respond poorly to routine care.
In the somatoform category, DSM-IV-TR includes diverse diagnoses such as conversion disorder, hypochondriasis, pain disorder, and body dysmorphic disorder. But like mismatched shoes, these disorders do not fit together well—one reason they are often misdiagnosed and ineffectively treated. This article describes:
- debate about how to categorize somatoform disorders—as psychological or physiologic
- evidence supporting psychotherapy and antidepressants to help patients with treatment-resistant somatoform disorders.
Somatoform disorders: Interacting psychiatric and biologic processes
Psychobiologic causes of somatoform disorders are poorly understood. In a recent review, Rief and Barsky1 emphasized that somatoform symptoms such as abdominal pain, headaches, or dizziness “are not strictly mental events, but are associated with a diversity of biological processes.” They propose that the following factors might contribute to somatoform disorders.
Autonomic physiologic arousal may lead patients to misperceive the meaning of normal bodily symptoms, but most studies have been equivocal or correlate closely with changes in the cardiovascular system. For example, patients with somatoform spectrum disorders who performed mentally distressing tasks did not have the same decrease in heart rate after completing the task as normal controls did, suggesting a deficit in autonomic reactivity.
Hypothalamic-pituitary-adrenal (HPA) axis studies also have been equivocal. Some have found low cortisol in patients with somatoform disorders—suggesting commonalities with conditions such as posttraumatic stress disorder—but other studies have found normal or even elevated cortisol. Although a relationship between the HPA axis and somatoform disorders is likely, its nature remains unclear or may be indirect.
Serotonin is known to alter pain perception in major depressive disorder, so this neurotransmitter also probably plays a role in somatoform disorders. Low serotonin—mediated in part by alterations in branched-chain amino acid concentration—may be linked to increased pain perception.
Perception and filtering of body signals. A signal-filtering model of somatoform symptoms proposes that physical sensations enter consciousness influenced by numerous factors. These signals are then sent to a filter system, which itself is subject to factors that may decrease its activity. Cortical perception of distress may occur and symptoms begin to manifest if enough factors come into play.
Which category?
Somatoform disorders are common in primary care. A medical utilization survey of 1,500 primary care patients found somatization symptoms in >20%.3 Controlling for comorbid psychiatric or medical illness did not change the study’s findings, which suggests that somatization is a distinct entity and not a symptom of another underlying disorder.
Little is known about somatoform disorders’ pathophysiology (Box 1),1 but their unifying theme is that psychological factors contribute to, amplify, or alter the presentation of physical illness. Not only do these disorders not form a coherent DSM category, but—as described by Mayou et al2—the lack of clearly defined thresholds between normal and pathologic behaviors is one of numerous problems that complicate diagnosis and treatment (Box 2).
Psychosomatic diad. Despite DSM-IV’s claims to etiologic neutrality, the origin of somatoform disorders’ physical symptoms clearly is meant to be psychological. As Lipowski4 said, somatization is “a tendency to experience and express somatic distress and symptoms unaccounted for by pathological findings, to attribute them to physical illness, and to seek medical help for them. It is often assumed that somatization becomes manifest in response to psychosocial stress brought about by life events that are personally stressful to the individual.”
Kroenke and others,5,6 however, have pointed out 2 shortcomings of this definition:
- the difficulty in knowing when a physical symptom truly is unexplained, especially in patients with comorbid medical illness5
- the instability of somatoform diagnoses (in a cohort examined with the same questionnaire 12 months apart, 43% of “lifetime somatic symptoms” patients reported at the first screening were not reported at the second).6
Similarly, Mayou et al2 contend that because most patients with somatoform disorders are treated by primary care physicians, having their disorders understood as psychiatric does not serve them well.
Psychiatric component. Conversely, patients with somatization disorder often have psychological symptoms, and many have personality disorders. The number of somatic symptoms with unexplained cause may be a normally distributed trait, with somatization disorders at the extreme end of the spectrum. Thus: