Sensitization and Its Discontents: Allergists, Psychiatrists, and the Limits of Medical Knowledge

Note to readers: This is my final editorial as Editor-in-Chief. It has been an honor and a privilege to have written in this capacity for nearly four years, and I thank both the staff of Psychiatric Times and its readers for their active engagement and collegial support.

It’s an embarrassment, no doubt about it. For those of you who have been following the intense debate over the DSM-5, it’s high time to ask: How much longer will the public put up with a medical specialty like this?

–A government report finds the field is rife with poorly done studies, misdiagnoses, and tests that give misleading results.¹
–Patients often “shed” the disorder commonly diagnosed by specialists in the field, and no one knows why.
–Specialists can’t agree on a definition of the condition they are treating.
–There is good reason to suspect “over-diagnosis,” owing to inadequate or inappropriate evaluation.
–One of the most common treatments used by specialists in the field has uncertain benefits, based on published studies.

I know: You are shrugging your shoulders, saying, “So what else is new? People have been saying these things about psychiatry for years!” Well, yes, they have, but-the conclusions above are from the latest report on a subspecialty within the “hard science” of immunology: the field of “food allergies.”

A systematic review by Dr Jennifer J. Schneider Chafen and colleagues, published in JAMA (May 12, 2010)² found that “…the evidence for the prevalence and management of food allergy is greatly limited by a lack of uniformity for criteria for making a diagnosis.” Indeed, the lead author, Dr Chafen, is quoted as saying, “Everyone has a different definition” ¹ of a food allergy. Apparently, over 80% of the studies reviewed by Chafen and her colleagues used their own definition of “food allergy.” Furthermore, the common practice of identifying food allergies by measuring levels of IgE antibodies in the patient’s blood proved to be an unreliable test. Prof. Joshuah Boyce, an allergist at Harvard, observed, “There are plenty of individuals with IgE antibodies to various foods who don’t react to those foods at all.”¹ And the coup de grace? The common practice among allergists of advising the patient to give up the implicated food-so-called “elimination diets”-is of uncertain and untested benefit.²

Now, to be clear: My aim is not to cast aspersions on our allergist colleagues; nor is it my intent to give the field of psychiatry a “free pass” on its own shortcomings, which are numerous. Rather, I want to debunk a widespread misconception about psychiatry, as contrasted with other medical specialties. That popular myth goes something like this: Other medical specialties are based on “hard science,” known pathophysiology, objective diagnosis, reliable laboratory tests, and well-validated biomarkers. Psychiatry, the myth insists, lacks each of these characteristics.

I’ll acknowledge the force of the “hard science” argument, if we compare psychiatry to, say, mechanical engineering or physical chemistry. But when we hold psychiatry up to the other medical specialties, we find many more similarities than differences. In each such comparison, we find that the medical specialties in question are struggling with many of the same conceptual and diagnostic conundrums as those besetting psychiatry. To cite just a few examples:

–In oncology: Identification of cells and tissues as “cancerous” or “malignant” is by no means straightforward, and many cases of “atypical” cells are notoriously difficult to classify. This is evident, for example, in the notion of “precancer,” as one recent review pointed out: “…precancers are associated with a morphological continuum from atypia to dysplasia and invasive neoplasia.”³ The notion of a “continuum” of pathology should sound eerily familiar to psychiatrists following the DSM-5 controversies.

–In neurology: The classification and diagnosis of headaches has undergone considerable change in the past 20 years. In the most recent international classification of headache disorders (ICHD-II), more than a hundred different kinds of headache are categorized, most of which lack a clearly-defined pathophysiology. One expert, commenting on migraine headaches, observed that

“Lacking an external “gold standard” for headache diagnosis, validity is difficult to judge. Migraine diagnosed according to ICHD criteria responds in 80% to 90% of treatments to injected triptans, drugs that can claim a highly specific mode of action. This proves that clinical diagnosis according to ICHD has been able to identify a group of patients who share a reasonably uniform response to pharmacologic intervention and presumably then share a common pathophysiological pathway.”⁴

Well, that word “presumably” is the elephant in the neurologists’ examining room. If psychiatrists made the claim, “80% of patients with severe, melancholic major depression respond to ECT (which is true); therefore, presumably these patients share a common pathophysiological pathway,” we would be summarily laughed out of the room--particularly if philosophers of science happened to be listening! A more modest assessment of the ICHD–II is provided by neurologist J.W. Swanson:

“The ICHD-II will not be the final word on headache diagnosis and classification. It will undoubtedly be significantly revised as more studies are done to delineate the science of headache. In this regard, the ICHD-II is not unlike the revisions of diagnostic and classification systems that have been developed in multiple areas of medicine such as psychiatry and epilepsy.”⁵–In rheumatology: The nature and diagnosis of “fibromyalgia” (“chronic fatigue syndrome”) remain mired in controversy, even as the condition has been recognized as a medical syndrome by nothing less than the Centers for Disease Control. The underlying pathophysiology and optimal treatment of fibromyalgia remain matters of intense debate. One review by 2 forensic psychiatrists-published in a rheumatology journal-concluded that “…the only certainty in fibromyalgia is that it is still being diagnosed…” and opined that “…society and medicine have to turn to philosophy rather than to science for the solution of treating and preventing ‘syndromes’ like fibromyalgia.”⁶

But psychiatry and the other medical specialties share more than their struggles with disease demarcation and diagnosis. We also have a practical, everyday clinical issue in common: the high prevalence of psychiatric and mental health problems in many general medical settings. As David Kupfer, MD, and Darrel Regier, MD, MPH, chair and vice chair, respectively, of the DSM-5 task force, pointed out in a recent editorial, “… in primary care settings, approximately 30% to 50% of patients have prominent mental health symptoms or identifiable mental health disorders, which have significant adverse consequences if left untreated.”⁷

In recent years, psychiatry has witnessed impressive growth in its integrated understanding of the biological and psychosocial components of brain-mediated disease, as Nobel laureate Dr Eric Kandel has shown.⁸ This is no time to marginalize or “uncouple” psychiatry from the rest of medicine, as some have suggested. Yes, we have a long way to go, with respect to identifying the genesis, pathophysiology and optimal treatment of the illnesses we confront-but the same may be said of most medical specialties. Psychiatry is, and should remain, well within the fold of general medicine.

References
1. Kolata G. Doubt is cast on many reports of food allergies. New York Times. May 11, 2010. Available at: http://www.nytimes.com/2010/05/12/health/research/12allergies.html. Accessed May 25, 2010.
2. Chafen JJS, Newberry SJ, Riedl MA, et al. Diagnosing and managing common food allergies: a systematic review. JAMA. 2010;303:1848-1856.
3. Cardiff RD, Borowsky AD. Precancer: sequentially acquired or predetermined? Toxicol Pathol. 2010;38:171-179.
4. Olesen J. The International Classification of Headache Disorders. Headache. 2008;48:691-693.
5. Swanson JW. Changes in the international classification of headache disorders. Curr Neurol Neurosci Rep. 2004;4:95-97.
6. Hazemeijer I, Rasker JJ. Fibromyalgia and the therapeutic domain. A philosophical study on the origins of fibromyalgia in a specific social setting. Rheumatology (Oxford). 2003;42:507-515.
7. Kupfer DJ, Regier DA. Why All of Medicine Should Care About DSM-5. JAMA. 2010;303:1974-1975.
8. Kandel ER. Psychiatry, Psychoanalysis, and the New Biology of Mind. Arlington VA: American Psychiatric Publishing; 2005.