What's So Important About Psychiatric Diagnosis?

When I was in graduate school, I stopped by a professor’s office to chat. During the course of our conversation, he asked, “Have you read Paul Meehl’s Why I Do Not Attend Case Conferences?” I confessed I had not. “You should read it,” he said, smiling. It was the best kind of reading recommendation: personal, absent a sales pitch, and delivered with a hint of mysterious subversion, like a Soviet-era samizdat.

Rarely has a casual recommendation had such an impact on me. Paul Meehl (1923-2003), a professor of psychology at the University of Minnesota, was the most influential clinical psychologist of the 20th century. Not coincidentally, he was a practicing clinician as well as a researcher and theoretician. Reading Case Conferences was an excellent introduction to Meehl's brilliant mind, and led me to read dozens more of his articles (as you can, here.)

There is an unforgettable passage in Case Conferences, in which Meehl encounters a clinical psychology trainee, bereft at the recent death by suicide of a patient. Meehl offers to talk to the trainee about it, but rather than offering "there, there" platitudes, he asks pointed questions: What was the patient's diagnosis? Was the patient experiencing a psychotic depression? What is the suicide risk of patients with that diagnosis? What was the patient's presentation prior to being let out of the hospital on that fatal weekend pass?

The trainee cannot immediately recall the diagnosis, a sign that the importance of psychiatric diagnosis was never drilled into him by his supervisors or professors. The trainee is unable to articulate the signs of psychotic depression (e.g., mutism) and does not know that the suicide rate for untreated psychotic depression is one-in-six (Russian roulette odds). He does not know that when severe depression is lifting is when a patient with psychotic depression is at greatest risk for suicide. Meehl's impatience with such substandard practice is palpable:

MEEHL: "You mean you have never read, or heard in a lecture, or been told by your supervisors, that the time when a psychotically depressed patient is most likely to kill himself is when his depression is 'lifting'?"

STUDENT: "No, I never heard of that."

MEEHL: "Well you have heard of it now. You better read a couple of old books, and maybe next time you will be able to save somebody's life."

I am continually thankful that no one has ever had to say something similar to me, and that I have never had to say something similar to a trainee. The passage above drilled into me an abiding concern for the basic and facts statistics pertaining to mental health practice, as well as a passion for careful diagnostic assessment.

You might wonder, by the way, what drove Dr. Meehl's vehemence during the exchange with the student, beyond the recent death of the patient in question. He does seem to let the student have it with both barrels, when only one would have sufficed. As he relates in his autobiography, when he was 11 years old, Paul Meehl's own father died by suicide, after having embezzled money to play the stock market:

"Taunts by classmates showed me human cruelty, and doubtless this (plus reading history) is why my view of mankind is closer to that of Freud and Luther than of Rogers and Rousseau. My mother began having frightening "heart attacks," and life seemed precarious indeed. At age twelve or thirteen I chanced upon Karl Menninger's The Human Mind, which was a healing Damascus experience. 'Why, these fellows have it all figured out, the workings of the mind follow scientific laws, it's like my chemistry set! My mother isn't going to die of heart failure, she's a young widow with anxiety neurosis.' I decided overnight to become a psychotherapist."

The death by suicide of Paul Meehl's father certainly might have influenced his reaction to the hapless student. Still further, when he was 16 years old, Meehl's mother died after surgery for a brain tumor. The tumor had been misdiagnosed by a well-respected internist as Meniere's disease "and he must never have rechecked her neurologically...while her condition steadily worsened over a year's time." As Meehl noted,

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"This episode of gross medical bungling permanently immunized me from the childlike faith in physicians' omniscience that one finds among most persons, including educated ones. It has also helped me to avoid dogmatism about my own diagnostic inferences, to which I am tempted by my self-concept as a naturally gifted and well-trained clinician."

Paul Meehl learned, in the harshest possible manner, the consequences of getting a diagnosis wrong. The importance of proper diagnosis is as critical in mental health as it is in other branches of medicine. Certain illnesses respond best to certain treatments, and not at all to others. There are no "one size fits all" mental health treatments, either psychopharmacological or psychotherapeutic.

Not all diagnostic errors are as dramatic as that of Meehl's mother, or that of the composer George Gershwin, who was repeatedly treated for depression while a once-operable tumor grew slowly within his brain. Perhaps the most common diagnostic error I encounter is the propensity of many psychotherapists to give the same diagnosis to almost all of their clients, i.e., Adjustment Disorder with Mixed Anxiety and Depressed Mood. Now, depression and anxiety certainly are the bread-and-butter of outpatient mental health, but that does not mean that many of those people given the "adjustment disorder" diagnosis don't actually have far more serious conditions that require more intensive interventions than mere supportive therapy.

As they are about to write "adjustment disorder" once again, therapists should ask themselves, "What if there were no such diagnosis? What would I put down then?" Often, "adjustment disorder" is chosen because it seems to be the least stigmatizing psychiatric diagnosis—negative life experiences could happen to anyone! But what if the patient really is experiencing Major Depressive Disorder? Would you be quite so sanguine about their reluctance to seek a psychiatric medication consultation? What if the true diagnosis is PTSD or OCD? Are you trained to deliver effective treatments for these disorders, or do you need to refer your patient to a specialist? Are these relationship issues and this chronic "moodiness" really adjustment disorder, or could it be Borderline Personality Disorder? Could the patient you've diagnosed with Borderline Personality Disorder actually have Bipolar I Disorder (or both disorders simultaneously)?

Some questions that therapists should ask themselves as they engage in the diagnostic process: What role is substance use playing in this patient's problems or presentation? Have I assessed thoroughly for psychotic processes, or might I be mistaking a paranoid process for "relationship difficulties"? Am I seeing the expected percentage of outpatients with personality disorders, eating disorders, suicidal ideation, traumatic brain injury, trauma exposure, etc.? If not, what's so exceptional about my practice that these patients aren't showing up here? (Rule of thumb: If fewer than 1-in-5 of your new patients report recent suicidal ideation, you are not assessing suicide risk well enough.)

A patient's diagnosis, arrived at correctly, is the most important prognostic indicator we have. Treatment decisions must be based on careful psychodiagnosis. Popular treatment approaches, such as mindfulness therapy, simply are not sufficient for all patients. Too many outpatient psychotherapists, practicing independently, with no one providing supervision or feedback on their performance, fall into substandard practice habits, the foremost of these being sloppy diagnosis. Do better, "read old books," and never stop learning facts and statistics relevant to good practice.