“Functional,” Reasons, Neuroscience and the Psychogenic Inference

Tyreman and Loughlin make many varied and interesting comments, but neither, it is encouraging to find, is prepared to defend the psychogenic inference. Indeed, Loughlin finds the paper “somewhat shocking.” “The psychogenic inference,” Loughlin writes, “seems such an obvious fallacy, yet he [Sykes] shows, with detailed reference to both diagnostic practice and the literature on mental disorders, the extraordinary pervasiveness of its influence, extending even to the systematic ambiguities built into key diagnostic terms” (2010, 305).

The main points of disagreement are Tyreman’s defense of the term functional in certain contexts and Loughlin’s criticism of the claim that there has been a paradigm shift in the views of modern neuroscientists. Loughlin also offers an alternative diagnosis of the error of the psychogenic inference. For reasons of space, I focus on these three points.

Discarding “Functional”

Tyreman wishes to retain the use of the word functional in three contexts: (1) Where it refers to the “global ability” of the patient, (2) where it indicates an adaptive response, and (3) where it indicates a maladaptive response. This gives me the opportunity to be more precise about the uses of the term functional that, in my view, should be discarded. In summary, in my view the term should not be used where there is the possibility that the term could carry the psychogenic inference, namely, where it could be understood to mean having a psychological cause. This means that in general it should not be used to distinguish one symptom or set of symptoms from another symptom or set of symptoms; in such uses, it may be understood as meaning to have a psychological cause. In other uses, there may be no objection to the continuing use of the term.

From this perspective, there are clear objections to using the term functional in the third context specified by Tyreman, namely, where there is a maladaptive response, where, for example, a short-term adaptation becomes a long-term disability. In this case, the term is being used to distinguish one kind of symptom from another and so is liable to be thought to carry the psychogenic inference.

Tyreman could claim that, as an osteopath, he is using the word functional in this context without making the psychogenic inference. (His explanation of functional in this usage involves a physical, not a psychological cause—”nerve impulses synapsing”). So why should not he, and other osteopaths, continue to use the term functional in this sense?

The problem is that in neurology, psychiatry, and medicine generally, the term functional when used to distinguish one symptom from another very often carries the psychogenic inference. Although osteopaths can use the term without any such inference, if medicine and the professions allied to medicine are to have a common language—and there are many very good reasons for this—then osteopaths need to give up their use of the term in the interests of a common language. This may be a bit hard on osteopaths, but replacements for the term will not be difficult to find. Perhaps maladaptive—the word that Tyreman himself uses—could be a suitable replacement in this context.

Similar considerations would seem to apply to his second use of functional—where there is an adaptive response. Tyreman’s explanation of this use of the term again invokes a physical cause—for example, physical injury, food poisoning—but, as argued, if this use is intended to distinguish one type of symptom from another, the same objections apply. In the interests of a common language, osteopaths need to give up this use of the term. Perhaps adaptive, the term that Tyreman uses, would be an appropriate substitute.

On the other hand, I see no problem in retaining the use of the word functional and its associated verb to function in the first context mentioned by Tyreman. This is the context where the word is used in connection with the “global ability” of a patient. “It is uncontentious,” he writes, “that health care practitioners work to improve patients’ functionality” (2010, 302). To this use of functional there are no objections...