A bit on the diagnostic system and clincal practice and why it's complicated

Psychiatry has often been compared to alchemy and astrology by brilliant
critical minds of the 20th and 21st century.

They should also acknowledge it is the best attempt at predicting a
person's future in the history of humankind, albiet a poor one still.
The clusters of symptoms have been developed with some of the best
sceitific positivisitc techniques available today. A diagnosis predicts
a prognosis or a life course. What that means is, according to the
psychiatric measures used, there is a higher probability of predicting a
person's outcomes than guess work, by using an operational definition of
a cluster of symptoms with, say, 5 out of 9 or 2 out of 6 being
sufficient to make this prediction.

A probabiliity, no matter how certain apart from 100%, is not a
certainty. This is addressed by practical measures such as valuing what
happens to 95% of people using the standard measure of confidence
interval. The probabilities involved in mental health are far from 100%.

There is an assumption based on a fundamental psychiatric idea that
every mental illness can be assigned a category, by which they mean
every type of person as described by the psychiatric system must fit
within a broad group. There is a difference between a schizophrenic and
a manic depressive, though this is a contentious idea long debated
throughout the history of psychiatry and confused by new diagnoses (soon
to be removed) such as schizoaffective disorder and the results of
genetics research which is confusing at best.

But that's totally irrelevant because what psychiatry is, at least to an
engineer's mindset, is what happens to people and what happens in
clinical practice. Lets take the diagnosis of schizoaffective disorder.
It is and it isn't inbetween schizophrenia and bipolar disorder. It was
found through a few studies that within the group of people with
psychotic disorders there was a vaguely defineable middle group that had
poorer outcomes that were better than people with a diagnosis of
schizophrenia and worse than people with a diagnosis of bipolar. The
characteristics of this group are defined by the cluster of symptoms in
either of the psychiatric bibles. If clinicians resolutely doggedly
stick to the research criteria and the differential diagnosis
information that helps clinicians give people the correct label then
schizoaffective disorder is a valid psychiatric diagnosis. Clinicians
don't and many assume it is simply inbetween schizophrenia and bipolar,
and that's ridiculous because of the Kraeplinian dichotomy anyway (are
bipolar and schizophrenia distinct or separate entities).

There is considerable evidence that clincians won't give the same
diagnosis to the same person, not least in my own life history. I don't
know what diagnosis I have at the moment. Schizophrenia, borderline
personality disorder, chronic depressive or just normal. I've had a
diagnosis of depression many years ago when I was at university. When I
was thrown out of home as a child I saw a psychiatrist and was declared
sane though that may not happen today. When I was first hospitalised I
was given a diagnosis of bipolar. Another psychiatrist (who saw me
longest) gave me a diagnosis of schizoaffective disorder. Upon my next
hospitalisation I got a diagnosis of dual diagnosis from another
psychiatrist (comorbidity - drugs, alcohol and mental illness). After a
subsequent hospitalisation I got a diagnosis of mixed affective disorder.

The program "How mad are you?" or whatever was a public-friendly example
of what had been shown in a study conducted in America at a psychiatric
conference. The conference allowed a large sample size of psychiatrists
and the experiment used actors with a standardised script. Psychiatrists
were simply asked to give a diagnosis based on the interview. The study
showed the largest factor in the high level of variance between
diagnoses given by the different psychiatrists wasn't on gender (of
patient or psychiatrist if I remember right), race or anything else that
I expected. The biggest factor was where they studied psychiatry. It was
the influence of their learning in their formative years that most
influenced the variance in diagnosis.

So psychiatrists and other mental health professionals don't stick to
the strict criteria as used in the studies that underpin the science of
psychiatry and evidence based medicine. They rely on other things such
as their personal and clinical experience, the advice of other doctors,
their gut feeling and all the other techniques that other people use in
their every day lives to make decisions.

At the moment they step away from the DSM or ICD criteria they lose all
the weight of the body of science that has gone into the diagnostic
system and revert to what mental health and diagnosis shouldn't be about
yet at the same time they take the risks necessary to be good, human
doctors. It is both human to make decisions in the spirit of the law
rather than the letter of the law....hmmm....hope that mixed bit of
language makes sense. Basically good doctors work out their own ways to
make a diagnosis - and this is true of many professions. Some doctors
can make better clinical decisions than are doctors who stick to the
book and strictly adhere to the criteria. However others who aren't as
naturally capable risk worse outcomes.