We're Diagnosing Like It's 1799

The fact that psychiatry lags far behind the rest of medicine scientifically is no great news flash. The leaders of our field have long acknowledged this problem (see, for example, this withering self-critique by then head of NIMH Thomas Insel).  None of this should be taken personally. Psychiatrists are just as smart as other doctors. It’s just that we have the misfortune of having chosen the most complicated organ to study—the brain.

Nonetheless, occasionally I come across information that reminds me anew of just how far in the dark ages we are stuck. This happened a couple of weeks ago when I was binge-listening to podcasts and happened upon this great episode of the 99% invisible podcast about the origin of the stethoscope.

The stethoscope was invented in 1816 by a 35 year old Parisian physician, René Laennec. Laennec was particularly interested in “diseases of the chest” as they were called then, and especially tuberculosis, which was ravaging Paris and had a 50% death rate. Doctors knew a little bit about how TB affected the lungs based on autopsy findings. But they didn’t have clue that what caused it (that would have to wait until 1882 when Robert Koch discovered mycobacterium tuberculosis), and they had a very hard time diagnosing the disease in a living person. TB causes symptoms such as dyspnea (shortness of breath), coughing up blood, weight loss, and fever, but many patients with other diseases presented similarly. Doctors had no diagnostic tools or blood tests, and depended on having long talks with patients about their symptoms and history. But conversations about an illness only got them so far, and commonly the final diagnosis was simply “dyspnea” or “fever”—which we now know are symptoms with various underlying causes, but which in the 18^th century were thought of as diseases.

A medical transformation was borne one day when Dr. Laennec was examining an overweight woman with dyspnea. Based on their conversation, Laennec could not distinguish TB, pneumonia, or heart disease. He tried chest percussion, a popular method that helps detect whether areas of the lung are filled with inflammatory fluid, but the abundance of tissue rendered that technique unhelpful. He was tempted to simply place his ear on her chest—a technique called “immediate auscultation,” but felt that it was “indelicate” to do so. He looked around and, in his words, “grabbed 24 sheets of paper, rolled them tightly into a bundle, and secured them in shape with paste glue.” Using this cylinder, he placed one end onto her chest, and other to his ear.  He was “delighted” to find that he could hear heart and breath sounds with amazing clarity.

Laennec refined the device over the next several years, hiring a carpenter to build better versions out of wood, and he shared his discovery with colleagues. Armed with the stethoscope, doctors carefully correlated breath and heart sounds of dying patients with autopsy findings, eventually reporting a series of “pathognomonic” sounds that could, with a good degree of certainty, diagnose specific diseases. Whereas patients were once told that their disease was “dyspnea,” they could now learn which organ was affected, and what the likely prognosis was. Unfortunately, effective treatment had to wait for the discovery of antibiotics and cardiac drugs.

In psychiatry, diagnostically we are squarely in the pre-Laennec era (though therapeutically, we have serendipitously discovered highly effective treatments for many disorders). We diagnose such entities as “major depression” and “schizophrenia” based on prolonged conversations with patients, conversations termed “mental status exams.” We combine our observations with the history to discover clusters of symptoms that often occur together, and which are therefore included as “disorders” in the DSM-5. But, like physicians in 1799, we don’t understand how the pathology of the underlying organ leads to these symptoms. In fact, our science is arguably considerably more primitive than 1799 medicine, because even our autopsy results have not identified any lesions responsible for psychiatric symptoms—with the exception of Alzheimer’s disease.

Psychiatry does not have a stethoscope. We have ancillary technologies, such as MRIs, PET scans, EEGs, and blood tests, all of which can effectively rule out other diseases that can mimic psychiatric disorders. But we can’t peer into our patient’s brain to tell them what lesion or circuit mishap causes them to suffer as they do.

We need to acknowledge that a careful interview is not only central to psychiatric diagnosis, but is the only method we currently have in our diagnostic tool box. If we really want to help our patients, we need to enhance our skills at asking the right questions and understanding the meanings of the answers. Which may well take more time than insurance companies believe we are worth.