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Mark Sullivan
University of Washington, Seattle, WA

Somatization is a common clinical problem. Physical symptoms without a clear origin in tissue pathology are ubiquitous in primary care medical practice. While persons in the community have a new physical symptom every 5 to 7 days, over 90% of these are never brought to the physician. The decision to seek medical care for a symptom is determined by the person's beliefs about the health care system, the symptom's importance, and its associated distress. Persons who seek medical care for headaches, fatigue and GI complaints have been shown to have more stressful life events, more psychological distress, and more anxiety and depressive disorders than those who do not seek care. Patients with anxiety and depressive disorders have more symptoms (medically explained and unexplained) than those without these disorders. Patients with depression have twice the health care costs of age and sex-matched patients without depression, even after adjustment for co-morbid chronic medical illness.

The concept of somatization has been criticized on scientific and ethical grounds. Its scientific validity has been questioned because somatoform disorders are basically diagnoses of exclusion. They are 'wastebasket' categories without clear positive diagnostic criteria. Bill Fordyce long ago criticized the use of psychopathology to patch holes in the ability of tissue pathology to explain pain. Somatization has also been criticized as a way of stigmatizing, blaming or dismissing difficult patients and their complaints.

One reason that somatization is controversial is that it has been difficult to specify its psychophysiological mechanism. Many clinicians assume that depression lowers pain threshold or pain tolerance. But well-replicated research shows that depression has no effect on pain threshold for external noxious stimuli and increases tolerance to these noxious stimuli. Thus at the center of somatization lies a paradox: clinical depression is associated with increased severity of physical symptoms, but in experimental models, depression is associated with increased tolerance of external noxious stimuli.

A. D. "Bud" Craig is a neuroscientist who has offered a new understanding of pain circuitry which sees it as more a part of internal homeostasis that external sensory perception. Pain is conventionally viewed as a pattern of convergent activity within the somatosensory system that represents the exteroceptive sense of touch. Accumulating functional, anatomical and imaging findings indicate that pain is generated by specific sensory channels that ascend in a central homeostatic afferent pathway. I believe this new view of pain as a'homeostatic emotion' can help bridge the gap between theories of somatization and sensitization. We will examine some recent findings concerning fibromyalgia, to see if this new theory helps reconcile the clinical and research findings.

Time of Presentation
Saturday 7 May 2005 - 1330-1500

References

1. Craig AD, Interoception: the sense of the physiological condition of the body, Curr Opin Neurobiol, 2003; 13:500-5.
2. Craig AD, A new view of pain as a homeostatic emotion, Trends Neurosci 2003; 26:303-7
3. Epstein RM, Quill TE, McWhinney IR, Somatization reconsidered: incorporating the patient's experience of illness, Arch Intern Med. 1999 Feb 8;159(3):215-22
4. Katon WJ, Sullivan MD, Walker EA: Medical symptoms without identified pathology: relationship to psychiatric disorders, childhood and adult trauma, personality traits. Ann Intern Med 134:917-925, 2001.