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The DSM5 – An idea whose time has come…and gone?


The APA’s relentless pursuit of “clinical homogeneity within diagnostic categories” is, by its own admission, doomed to failure. In no other branch of medicine do all patients with a given diagnosis look alike. Why should mental disorders magically be different? Nonetheless, the APA seems unable to kick the habit. This is why the DSM5 is obsolete before it has even hit the bookshelf.

The Diagnostic and Statistical Manual 5th Edition of the American Psychiatric Association has just been published, but it is already obsolete. The reason for its premature obsolescence is an outgrowth of the history of the document itself. The precursor of what eventually became the DSM appeared in 1840, as a catalog of mental disorders created to enable the US Census Bureau to gather information about the prevalence of mental illness in the US. In 1917, The Statistical Manual for the Use of Institutions for the Insane was compiled by the National Commission on Mental Hygiene and the American Medico-Psychological Association (the precursor to the American Psychiatric Association) . The DSM itself first appeared in 1942, and is now in its fifth revision.

At the time of its creation, the DSM (and its predecessors) represented a laudable attempt to bring order out of chaos. Lacking the diagnostic tools available to us today, the inner workings of the human brain remained a mystery. Freud– one of the founders of modern psychiatry — began his career in the late 1800s as a neuropathologist, but soon realized that the scientific tools necessary to connect brain science to the study of human behavior did not exist. He opted to turn away from brain-based research, focusing instead on the workings of the mind, divorced from considerations of anatomy or physiology. If Freud were alive today, however, we would probably find him sitting at the controls of a brain scanner, rather than performing psychoanalysis. Meanwhile, the profession of psychiatry is only now returning to its roots as a branch of neuroscience. Rooted as it is in the past, however, the DSM remains symptom-driven.

Since there was no direct way to study the living brain 100 years ago, researchers pinned their hopes on other avenues of investigation. Just as thousands of individual mosaic tiles can coalesce into a coherent image, they reasoned that a lengthy compendium of narrowly defined, mutually exclusive clinical syndromes would ultimately coalesce into a coherent portrait revealing the underlying principles governing mental illness and mental health. Alas, that hopeful premise has not been realized, for a very simple reason: The fundamental principle that underpins clinical classification – “Behaviors that appear similar belong together” — turns out to be untrue (just as birds, bees, and bats could all be classified as “creatures that fly,” for example, but there is greater value in classifying them according to other dimensions). The converse assumption – “Things that behave differently are unrelated”— is also untrue. Butterflies fly, and caterpillars crawl along the ground. But they are really “the same” creature, albeit at different points in its life cycle. (We will have lots more to say on this as it relates to ASD in a future post.)

The editors of the DSM5 describe it as “a historically determined cognitive schema imposed on clinical and scientific information…constructed of a large number of narrow diagnostic categories.” The authors acknowledge that this design is flawed: “A too-rigid categorical system does not capture clinical experience or important scientific observations. The results of numerous studies of comorbidity and disease transmission in families, including twin studies and molecular genetic studies, make strong arguments for what many astute clinicians have long observed: the boundaries between many disorder ‘categories’ are more fluid over the life course than DSM-IV recognized, and many symptoms assigned to a single disorder may occur, at varying levels of severity, in many other disorders… [The] historical aspiration of achieving diagnostic homogeneity by progressive subtyping within disorder categories no longer is sensible.” Nevertheless, the DSM5 clings to the same “historically determined” classification method as earlier editions. This approach may have been reasonable 50 years ago, before the contributions of neuroimaging, neurobiology, and genetics, but it is hard to defend today.

See these links for more on the history of the DSM


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