A single
book has come to dominate psychiatry. That is dangerous
THE
human brain is the most complex object in the known universe. It contains 100
billion nerve cells. Considering how complex that is, it goes wrong remarkably
rarely.
But
go wrong it sometimes does. Which is why, since 1952, the American Psychiatric
Association has published its “Diagnostic and Statistical Manual of Mental
Disorders”, the DSM. This book, the newest version of which will hit the shops
on May 22nd (see article),
contains the association’s thinking on what constitutes a disorder of the mind.
It is consulted not only by psychiatrists, but also by insurance firms, drug
companies and anxious patients and parents—not only in America, but around the
world. It has become the industry standard for defining what is and is not a
mental illness, and thus who gets treated, and who pays for treatment.
No
other major branch of medicine has such a single text, with so much power over
people’s lives. And that is worrying. Because in no other branch of medicine is
the scientific reality underpinning the pronouncements of doctors so uncertain.
The
categorical imperative
This
uncertainty flows from a profound ignorance about how brains actually work.
Neuroscientists understand how nerve cells work. They also know which bits of
the brain deal with vision, locomotion, language, memory and suchlike. But
between these two anatomical levels all is darkness. Psychiatrists have thus
had to use behaviour patterns as proxies for underlying problems. And what
constitutes a pattern is too often a matter of opinion rather than a
statistically rigorous fact.
It
is this desire to find and classify patterns which gives the DSM its power. By
naming things it gives shape to the fledgling science. That is not a bad thing
in principle. But in practice it has gone too far. The main criticisms are that
it medicalises normal behaviour and that the strict categories of mental
illness it creates are increasingly at odds with what research suggests is
actually going on in the brain.
Both
criticisms are ultimately about names. The DSM gives names like “disruptive
mood dysregulation disorder” to temper tantrums in children and “binge eating
disorder” to those who tend to overeat. If these were mere labels, perhaps it
would not matter (though in the area of mental health even a label can be
damning). But diagnosis frequently leads to prescription, and lots of pills are
thus being popped by people whose need to take them is, to say the least,
questionable.
The
way the DSM classifies those who unquestionably are ill is also under attack.
Schizophrenia, major depression and some forms of autism are disabling
conditions that have long been considered separate diseases. But modern techniques
of gene analysis and brain scanning are leading some researchers to wonder
whether they really can be distinguished in the way that, say, various forms of
leukaemia can be differentiated—for their biological underpinnings seem to
overlap. Without a proper diagnosis, proper treatment is hard.
Veneration
of the DSM is also harmful in research. Thomas Insel, the head of America’s
National Institute of Mental Health, has publicly encouraged scientists not to
be constrained by its approach, lest it prevent them finding diagnoses and
treatments. In terms of diagnosis, a few psychiatrists (including those who
conducted the genetics and brain-scanning studies) now publicly point to the
DSM’s deficiencies; yet the DSM’s definitions and certainties are too deeply
ingrained for this criticism to have hit home. The full consequences of that
will not be obvious for a long time. But the current over-reliance on one point
of view in this extremely uncertain science is healthy neither for psychiatry,
nor for those it treats.
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