|Copyright (c) 2009 by Kevin Thompson
The Meaning of Diagnosis
In the last issue, we reviewed the concept of diagnosis
, and discovered
that the popular conception of diagnosis does not correspond very
clostly to the reality. The popular understanding is that a diagnosis
describes the cause of an illness (such as a particular bacterial
infection), and provides guidance about the best type of treatment.
While this description is sometimes correct (such as for strep throat),
it often is not. Instead, a diagnosis is often a label applied to a set
of symptoms, such as bronchitis. Bronchitis
simply means an inflammation of the bronchi (the major passages leading
to the lungs), but says nothing about the cause of this inflammation.
The term doesn't even specify whether the inflammation is due to
a bacterial or viral infection, which is an important distinction,
given that antibiotics are useful for the former, but not the latter. A
physician may have reasons to suspect viral or bacterial origins, but
will not be able to identify a specific viral or bacterial strain.
Fortunately, these limitations are not critical for bronchitis, as the
viral form usually goes away in time without treatment, and antibiotics
usually suffice to deal with the bacterial form independent of which
bacterium is responsible. Unfortunately, this limitation becomes more
severe when applied to mental illness.
Diagnosis in Mental Illness
Unlike bronchitis, mental illnesses rarely come with any physical
symptoms that can be observed by a physician. Symptoms are almost
entirely internal to the patient's subjective world
(perceptions, thoughts, feelings), or behavioral in nature (angry
outbursts, spending sprees). Worse, the causes of mental illness
(believed to be abnormalities in brain chemistry, receptor
concentrations, and so forth) are not known at a level that is
detailed enough to provide an obvious connection between symptoms and
causes. Worst of all, no standard medical tests exist to detect the
underlying causes anyway.
Given the scarcity of useful knowledge and diagnostic tests, it is not
surprising that diagnosis is solely symptomatic. It is also dismayingly
subjective, as different psychiatrists can justifiably interpret the
same symptoms as indicating such widely different diagnoses as anxiety
and bipolar disorders. The fault here is not the physician's, but
rather the arbitrariness of the diagnostic categories, and the lack of
any objective criteria for measurement.
The final "dirty secret" of psychiatry is that medications used to
treat mental illness have a relatively low probability of success. The
probability that someone with depression will response well to any
single antidepressant, for example, is around 30%. Thus the average
patient may have to try a few different antidepressants before he gets
Any concept of diagnosis as a precise
description of an illness, which serves as a useful
guide to treatment, has almost disappeared from this picture. In fact,
the picture is so poor that any reasonable person would shake his head
and wonder why the mental-health profession persists with its practice
of fuzzy diagnoses and low-reliability treatments.
The answer, of course, is one that psychiatrists understand all too
well: as inadequate as this approach to diagnosis and treatment
may seem, it is the best that medical science can do.
Or is it?
Correlation in the Treatment of Illness
Let's pull back and remember that what the patient really wants is to
feel better. He cares about a diagnosis primarily because he sees it as
a necessary step to feeling better. However, if we have reached the
point where diagnosis is an unsatisfactory guide to treatment, perhaps
it is time to look at alternative strategies for meeting the patient's
What we really want is a predictive model than can determine which
treatment will work best for each patient. If a classic diagnosis
assists this result, then so be it, but if not, we should not allow the
expectation that diagnosis is necessary to get in the way.
The concept of a predictive model is simple: Given an initial state,
the model predicts the effects of different treatments, and we select
the treatment that produces the best results. To do this, we need a
quantitative description of the patient's state, and a method for
predicting how his state changes based on treatment. In simpler terms,
we need to know what "sick" and "healthy" mean in terms that can be
measured, and how different treatments will affect the person.
Note that the concept of diagnosis
has disappeared, and been replaced by the concept of correlation
The nature of the illness is irrelevant, because what matters is how
results are correlated with the possible types of treatment.
The concept of correlation provides a completely different paradigm
(organizing strategy) for how we think about illness and medicine. What
we lose is the concept of a diagnosis, meaning an understanding of why
we are ill. What we gain is a strategy for treating problems that
cannot be diagnosed in any meaningful sense. (Is the loss a serious
one? No, it isn't, because correlation methods are additional to
strategies for discovering treatments, not a substitute for diagnostic
strategies that work.)
One Correlation Method: Referenced EEG
A company named CNS Response
pioneered a correlation method based on electroencephalogram
technology, called "Referenced EEG" (rEEG). At the heart of the rEEG
method is a database of EEG recordings from thousands of healthy
individuals, and individuals suffering from some common mental
illnesses, both before and after taking various psychiatric
medications. The company has created a predictive model based on
statistical analysis of how different people respond to medications,
which allows them to predict the response of a specific person to
The claim is a bold one, and seems too good to be true. However, the
company does not claim perfect success, only a better success rate than
alternative strategies for selecting medications. For
example, a study of patients with refractory depression
(treatment-resistant depression) showed that six out of seven patients
treated with the rEEG method improved, compared to one out of seven
whose treatment was not guided by this method. The company claims an
overall success rate of 70 - 95% in treating depression,
attention-deficit disorder, eating disorders, and addiction.
These studies are sufficiently new that researchers in
psychopharmacology have not confirmed or generally supported the
results at this time. However, the relatively inexpensive and
uninvasive nature of the technique, coupled with the reported success
rates, make rEEG a technique definitely worth exploring.
While the concept of diagnosis remains valuable, it is no longer the
sole paradigm for the selection of medical treatment. The new
concept of correlation, while perhaps less intellectually satisfying,
provides a very different approach to finding effective treatment for
medical problems. Correlation methods hold out the prospect of
successful treatments in areas where traditional diagnostic techniques
have proven inadequate. Those who suffer from depression, and other
types of mental illness, have reason to be glad that a new correlation
method, rEEG, is now available to them.
Ph.D. is the author of
You can find information about treatments for depression, bipolar
disorder, schizophrenia, and sexual problems on his Web site at