Fuzzy Logic in CFS

Thanks to Tom K for finding this one:

Full text at: http://jech.bmj.com/cgi/content/full/62/3/273

Journal of Epidemiology and Community Health 2008;62:273-278;
doi:10.1136/jech.2007.063644
Copyright C 2008 by the BMJ Publishing Group Ltd.

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THEORY AND METHODS

Methodological insights: fuzzy sets in medicine
P Vineis

Correspondence to:
Paolo Vineis, Imperial College London, Department of Epidemiology and Public
Health, Norfolk Place, London W2 1PG, UK; p.vineis@imperial.ac.uk


Accepted for publication 3 July 2007


In this paper I wish to introduce some ideas about scientific reasoning that
have reached the epidemiological community only marginally. They have to do
with how we classify things (diseases), and how we formulate hypotheses
(causes). According to a simplified and currently untenable model, we come
to defining what a disease, or a protone or a chromosome, is by progressive
simplification-that is, by extracting an essence from the individual
characters of disease. At the end of this inductive process a single
element, which guarantees the unequivocal inclusion in the category, is
identified. This is what has been called "Merkmal-definition" (Merkmal
meaning distinctive sign)-that is, the definition of disease would be
allowed by the isolation of a crucial property, a necessary and sufficient
condition, which makes that disease unique (and a chair out of a chair, a
proton out of a proton, etc). However many objections have been raised by
Wittgenstein, Eleanor Rosch and others to this idea: a Merkmal is not always
identifiable, and more often a word is used to indicate not a homogeneous
and unequivocal set of observations, but a confused constellation with
blurred borders. This constellation has been called a fuzzy set and is at
the basis of the semantic theory of metaphors proposed by MacCormac and the
prototype theory proposed by Rosch. In this way the concept of disease, for
example, abandons monothetic definitions, amenable to a necessary and
sufficient characteristic, to become "polythetic." I explain how these
concepts can help medicine and epidemiology to clarify some open issues in
the definition of disease and the identification of causes, through examples
taken from oncology, psychiatry, cardiology and infectious diseases. The
definition of a malignant tumour, for example, seems to correspond to the
concept of "family resemblance," since there is no single criterion that
allows us to define unequivocally the concept of cancer: not morphology
(there are borderline situations between benign and malignant), not clinical
features, not biochemical or molecular lesions. In the case of
schizophrenia, the problem of indetermination, as it has been defined, is
even stronger. Mental disease probably cannot be distinguished from health
in a clearcut way (according to a minimum set of necessary criteria), but it
would have a fuzzy border with mental conditions that characterise normal
subjects, through intermediate linking conditions.

[..]

We can imagine a historical reconstruction of causality in medicine
according to two vectors, the definition of the causal agent and the
diagnostic process, and considering the transition from monothetic to
polythetic concepts along both vectors. Smallpox is a monothetic disease
both according to the definition vector (the poxvirus) and for symptoms and
signs; tuberculosis is monothetic on the aetiological axis but polythetic on
the symptoms/signs axis. And many "new" diseases (bulimia, psychiatric
diseases, autoimmune disorders) are polythetic along both vectors. Some
diseases have shifted from a monothetic form (with a "typical" presentation,
characterised by evident symptoms, easily interpretable) to polythetic or
borderline forms: one example is diabetes, which centuries ago was diagnosed
by the sweet taste of urine and now is at the border of normality through an
intermediate category (glucose intolerance). A very clear example of such a
transition is told by Aronowitz, "from myalgic encephalitis to yuppie
flue."12 In 1934 in California there was an apparent epidemic of
poliomyelitis, with as many as 2648 cases reported in the first seven months
of the year. In fact, the symptoms were mild (it was not the classic
paralytic form), to the point that several commentators spoke of "collective
hysteria." Something very similar happened in the 1980s with the "chronic
fatigue syndrome," a condition characterised by weakness and muscle pain,
which arose mainly after a viral infection in middle-class subjects. Also in
this case the lack of objective signs and, therefore, of a diagnostic test,
and the lack of an aetiological explanation, make of the disease a typically
polythetic condition, which includes probably both genuine post-viral
syndromes and psychological distress, or even a specific chronic tiredness
(the yuppie disease).

[12) Aronowitz RA. Making sense of illness: science, society and disease
Cambridge: Cambridge University Press, 1998.]

* * *

This has been the problem -- because of the way the revised criteria were written, "both genuine post-viral syndromes and psychological distress" have been lumped into CFS, making it impossible to find one cause or one cure, because they're looking at so many different things masquerading under one name.

As one of the original Incline Village patients continually reminds us, the Incline Village disease (which was actually M.E.) is what name ORIGINALLY applied to.  Anything else being passed off as CFS is a misnomer; whether intentional (to "prove" we're just nutjobs) or accidental (doctors who don't know anything about CFS except "fatigue").