But as all those Diagnostic and Statistical Manuals have stated clearly in their introductions, while the book seems to name the mental illnesses found in nature, it actually makes “no assumption that each category of mental disorder is a completely discrete entity with absolute boundaries dividing it from other mental disorders or no mental disorder.” And as any psychiatrist involved in the making of the D.S.M. will freely tell you, the disorders listed in the book are not “real diseases,” at least not like measles or hepatitis. Instead, they are useful constructs that capture the ways that people commonly suffer. The manual, they go on, was primarily written to give physicians, schooled in the language of disease, a way to recognize similarities and differences among their patients and to talk to one another about them. And it has been fairly successful at that.
Still, “people take it literally,” one psychiatrist who worked on the manual told me. “That is its strength in a political sense.” And even if the A.P.A. benefits mightily from that misperception, the troubles on the front page are not the organization’s fault. They are what happens when we expect the D.S.M. to be what it is not. “The D.S.M. has been taken too seriously,” another expert told me. “It’s the victim of its success.”
Psychiatrists would like the book to deserve a more serious take, and thus to be less subject to these embarrassing diagnostic squabbles. But this is going to require them to have what the rest of medicine already possesses: the biochemical markers that allow doctors to sort the staph from the strep, the malignant from the benign. And they don’t have these yet. They aren’t even close. The human brain, after all, may be the most complex object in the universe. And the few markers, the genes and the neural networks, that have been implicated in mental disorders do not map well onto the D.S.M.’s categories.