To the Editor:
The reported finding that “Hyperactivity, Thyroid Abnormalities May Be Linked in Some, Study Finds’’ (April 21, 1993) is another illustration of the untenable conclusions researchers will muster when determined to provide “evidence’’ that so-called attention-deficit-hyperactivity disorder, or A.D.H.D., is of biological origin.
The specific correlations in the study are fairly straightforward and acceptable: People with a resistance to thyroid hormone are more inattentive, distracted, and impulsive than their relatives who do not have the disease. Beyond this finding, one takes a huge leap of faith when trying to imply that the study has anything to do with something called an “A.D.H.D. disorder.’' Another leap is taken, this one away from basic logic, when suggesting, in the words of the first author of the study, that the correlations are evidence that “A.D.H.D. is something that is physiologically based and there’s a genetic cause for it.’' This implication is also the subtext of the editorial accompanying the article in the New England Journal of Medicine.
To take the illogic first: By finding psychiatric symptoms linked to a medical condition, one cannot conclude that the symptoms are “physiologically based.’' For example, mitral valve prolapse, chronic obstructive pulmonary disease, Cushing’s syndrome, and hyperthyroidism are among the many medical conditions that can produce anxiety. Even so, no one would turn this connection around and propose that anxiety is fundamentally biological in origin.
Without question, some biological states--for example, lead toxicity, food allergies, and certain medical conditions--can make youngsters and adults extremely inattentive and distractible--and worse. Nonetheless, simple logic must be applied when drawing conclusions about the causes of the latter behaviors, especially when they are said to have something to do with the “A.D.H.D.’' disorder.
That people in the study had a variety of inattentive behaviors is certain. Saying these behaviors represent “A.D.H.D.’' begs the question. Here, because of space constraints, I can only state that although many school children are distracted, etc., whether their behaviors constitute a “disorder’’ remains a conjecture; that believers, finding themselves at one dead-end after another, have been conceptually mutating the disorder for a half-century--from minimal brain damage to minimal brain dysfunction to hyperactivity to attention-deficit disorder with and without hyperactivity, to its present permutation; and that, in the previously published words of the second author of the study (Alan Zametkin), this history has produced no more than “speculation about the pathophysiology of A.D.H.D.’'
Speculation certainly is a central part of all scientific inquiry. However, as I discuss at length in The Learning Mystique: A Critical Look at “Learning Disabilities,’' a century-long line of speculative and misleading research determined to locate the source of children’s problems “inside’’ them, has fostered harmful diagnostic and classification practices in education and psychology and, concomitantly, has impaired the pursuit of a genuine understanding of, and solutions to, attention and learning difficulties.
Gerald S. Coles
Associate Professor of
Clinical Psychiatry
University of Medicine and
Dentistry of New Jersey
Piscataway, N.J.
