The word "diagnosis" comes from the Greek "to recognize" or "to know." The concept is an ideal in medicine, where to recognize and understand a disease is a prerequisite to treating it properly. Despite advances in science, history teaches that we usually know less than we'd like to about the causes of illness. This is particularly true when it comes to mental health.
Today's promise is that science will lead us out of the thicket. Researchers are decoding the genome, sorting out the functions of brain regions and mapping neural pathways. They'll be able to tell us what goes wrong, where it goes wrong and—eventually—how to fix it. Having reduced human experience to its fundamental biological elements, psychiatric diagnosis will finally be definitive and treatment choices will be precise.
Not so fast.
As the American Psychiatric Association ramps up to revise its Diagnostic and Statistical Manual (DSM), with a target publication date of 2012, signs are that the diagnostic system will improve. But no one doubts that the next edition will be the same as prior versions in one important respect—a work in progress.
Despite what the word means in Greek, "diagnosis" has a less lofty, more practical meaning in English. A diagnosis is a label, one that comes to represent a disease or a syndrome that is maladaptive or causes distress. Diagnoses are part of professional language. When a mental-health professional describes someone as having a "generalized anxiety disorder," another professional across town or across the country will have a good idea of how that term is being used.
The politics of psychiatric diagnosis, however, are not so straightforward. For one thing, people cherish their individuality and resist being labeled. Also, the power to name is significant. Diagnostic labels, when misapplied, can establish people as deviant, deprive them of rights or heap upon them a burden of shame or stigma. Even when intentions are good, diagnostic systems—like the science they are rooted in—are inevitably constrained by the intellectual, ethical and political trends of the era.
In the last 55 years, psychiatry has seen two extremes in the approach to diagnosis—one was individualized, improvisational and impressionistic; the other has been reliable, but too constraining. In 1952 and 1968, when the first and second editions of the DSM were published, psychoanalytic principles were ascendant and psychiatric practice had largely moved out of the asylum and into medical schools, outpatient clinics and private offices. In contrast to earlier views that mental illness was either hopeless or the product of a moral failing, the period after World War II was a time of great optimism in psychiatry. Illness could be understood as the result of derailed human development, or arising from conflict between biological drives and the environment. Such problems were thought to be correctable through psychotherapy.
DSM-I and DSM-II, unlike later editions, did not include detailed symptom lists, because disorder was presumed to be the result of processes that could not easily be seen. They could be deduced in a specialized therapeutic conversation. A prevailing view, and still an attractive ideal, was that each illness—and therefore each treatment—was one of a kind.
That was the good and the bad news. We like to be treated as individuals, but if each treatment is the first of its kind, it is impossible to garner evidence that might help you choose the most effective treatment. DSM-III, published in 1980, was an attempt to correct this, and it did so emphatically. By the 1970s, the limitations of psychotherapy (along with its benefits) were becoming clearer and new treatments were starting to take hold. With the rise of psychopharmacology, psychiatrists sought more dependable categories of illness. Following an era when diagnosis was heavily influenced by the theory and experience of the practitioner, the authors were determined to establish more reliable diagnoses based on strict descriptions alone. DSM-III and its successor purposely left theory out.
But this system did not make diagnosis more valid. After a quarter century of basic research, we know much more about how the brain works and which treatments are effective, but we are not yet close to mapping psychiatric disorders to specific biological or environmental causes.
What's next? Here's a prediction: DSM-V authors will approach their work with a generous attitude toward human nature, and will create a diagnostic system consistent with today's scientific knowledge. They will offer it, not as the last word, but as a tool for testing hypotheses about mental suffering. After all, good science is about getting it both right and wrong. And wisdom—with all due respect to the Greeks—is about appreciating how much we do not know.