Sunday, May 5, 2013

Psychiatry Finally Encounters Science—and Rejects It

Psychiatry is unique among the medical disciplines in that there is no science that supports the diagnoses made and the treatments prescribed by the practitioners. Gary Greenburg posted a note at The New Yorker that suggested that this lack of a scientific basis, once a source of unease within the discipline, has come to be perceived as a benefit in the practice of psychiatry. Greenburg titled his article Does Psychiatry Need Science?

"....doctors in most medical specialties have only gotten better at sorting our suffering according to its biochemical causes. They have learned how to turn symptom into clues, and, like Sherlock Holmes stalking a criminal, to follow the evidence to the culprit. With a blood test or tissue culture, they can determine whether a skin rash is poison ivy or syphilis, or whether a cough is a symptom of a cold or of lung cancer. Sure-footed diagnosis is what we have come to expect from our physicians. It gives us some comfort, and the confidence to submit to their treatments.

"But psychiatrists still cannot meet this demand. A detailed understanding of the brain, with its hundred billion neurons and trillions of synapses, remains elusive, leaving psychiatry dependent on outward manifestations for its taxonomy of mental illnesses."

Psychiatrists develop diagnoses by observations of patients and by assessing self-reported symptoms of patients. They use the same approach in determining the efficacy of treatments.

"Indeed, it has been doubling down on appearances since 1980, which is when the American Psychiatric Association created a Diagnostic and Statistical Manual of Mental Disorders (D.S.M.) that intentionally did not strive to go beyond the symptom. In place of biochemistry, the D.S.M. offers expert consensus about which clusters of symptoms constitute particular mental illnesses, and about which mental illnesses are real, or at least real enough to warrant a name and a place in the medical lexicon."

The D.S.M. provides a cookbook approach whereby symptoms can be catalogued and compared with possible mental illnesses. Of course, a set of symptoms need not be uniquely associated with a specific illness so it is of limited precision. Its main strength is in its simplicity and its authority. It can be interpreted and used to make a diagnosis by anyone capable of reading: parents, teachers, school nurses, psychologists, and medical doctors with no training in psychiatry. Because it is produced by a medical association it is assumed to have the same authority as a similar document produced by any science-based medical profession.

"But this approach hasn’t really worked to establish the profession’s credibility. In the four revisions of the D.S.M. since 1980, diagnoses have appeared and disappeared, and symptom lists have been tweaked and rejiggered with troubling regularity, generally after debate that seems more suited to the floors of Congress than the halls of science. The inevitable and public chaos—diagnostic epidemics, prescription-drug fads, patients labelled and relabelled—has only deepened psychiatry’s inferiority complex."

Did psychiatry still feel uncomfortable with its lack of a physical basis for their actions, or had they become comfortable with the simplicity it provided? Greenberg became suspicious when he observed what transpired when a group of experts advocated adding the diagnosis of the condition known as melancholia.

"A group of seventeen prominent doctors—biological psychiatrists, experts in diagnostics, subspecialists in the field of depression, and even a historian—petitioned the D.S.M.-5s mood-disorders committee to add a diagnosis they named melancholia."

"The proposal was not so much an innovation as a retrieval of an old idea. Melancholia is one of the most venerable of psychiatric disorders, noted by doctors at least as far back as Hippocrates, who attributed its characteristic dejection and unresponsiveness to external events to an excess of black bile. But melancholia lost its place in psychiatric nosology [disease classification] in 1980, when all forms of depression were consolidated under a single diagnostic label—‘major depressive disorder’—of which melancholia was only a variant. It was the D.S.M. equivalent of calling Pluto just another ice dwarf in the Kuiper Belt."

The group argued that melancholia was, in fact, a unique disease. While it had observable symptoms that might be confused with manifestations of other forms of depression:

" unshakeable despondency and sense of guilt that arises from nowhere, responds to nothing, and dissipates for no apparent reason—also displayed some distinctive physical signs: hand-wringing, for instance, and psychomotor retardation, an easily perceived slowing down of movement, thought, and speech."

The petitioners could provide evidence that melancholia could be detected by medical tests while other forms of depression could not.

"But some of the group’s proof was of precisely the kind that psychiatrists had been looking for since the nineteenth century. Thirty years of replicated studies had shown that patients with those signs and symptoms had a sleep architecture and cortisone metabolism that was distinct from that of other people, both normal and depressed. A night in a sleep lab could detect the reduced deep sleep and increased REM time characteristic of melancholics, and a dexamethasone suppression test (D.S.T.) could determine whether or not a patient’s stress hormones were in overdrive, as is generally the case among melancholic patients. And melancholia responded better than other kinds of depression to two treatments: tricyclic antidepressants (the first generation of the drugs) and electroconvulsive therapy (E.C.T., better known as shock therapy). Treatment success rates with this population reached as high as seventy per cent, much more robust than the anemic results found in trials that mixed melancholic and non-melancholic depression...."

One might have expected psychiatry to be thrilled with this request.

"Distinctive signs, symptoms, lab studies, course, and outcome—if melancholia wasn’t the Holy Grail, it was at least a sip from the chalice of science, one disorder that could go beyond appearances. You would think that the committee would at least have been eager to consider it as a partial remedy for ongoing concerns about the profession’s lack of scientific rigor."

But one would have been wrong.

"But the panel barely gave melancholia the time of day, let alone a full-on floor debate, relegating it to the same slush pile as the proposed Parental Alienation Syndrome and Male-to-Eunuch Gender Identity Disorder."

Incredibly, it was the scientific basis for the diagnosis and treatment that rendered it unacceptable to the D.S.M. committee.

"And the main obstacle was exactly what you would think was melancholia’s main strength: the biological tests, especially the D.S.T. ‘I believe you and your colleagues are fundamentally correct,’ committee member William Coryell wrote to the melancholia advocates, by way of explaining his panel’s inaction. But ‘the inclusion of a biological measure would be very hard to sell to the mood group.’ Coryell explained that the problem wasn’t the test’s reliability, which he thought was better than anything else in psychiatry. Rather, it was that the D.S.T. would be ‘the only biological test for any diagnosis being considered’."

As Greenberg so aptly summarized:

"A single disorder that met the scientific demands of the day, in other words, would only make the failure to meet them in the rest of the D.S.M. that much more glaring."

Science marches on, but psychiatry has found a sweet spot where it is comfortable and willing to live for the foreseeable future with diagnosis and treatment by committee revelation.

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