Debating the dodo verdict: Does one form of psychotherapy work better than another?

Health and medicine explained.
June 29 2011 12:46 PM

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Does one form of psychotherapy work better than another?

The Dodo. Click image to expand.
Is there a "dodo-bird verdict" effect in psychotherapy?

Soon after Alice descends into Wonderland in Lewis Carroll's novel, she and the Mouse, the Duck, the Eaglet, and the Lory find themselves competing in a race with no clear beginning or end. A half-hour later they ask the organizer of the event, the Dodo, to name a victor. The bird mulls it over and then proclaims, "Everybody has won, and all must have prizes."

For 75 years, the same dictum has been applied to the study of psychotherapy: Alice and the animals are like patients who each choose their own form of treatment and find their own path to happiness. It doesn't matter which style of therapy they get, Freudian or cognitive-behavioral or interpersonal, because in the end, everybody feels better.

We know that therapy works—studies find it's about as useful as antidepressants for treating moderate to severe depression—but curiously, these benefits seem to be realized irrespective of the therapists' theoretical beliefs. This effect—or rather, this appraisal of the field of psychotherapy—is called the dodo-bird verdict. All patients get a prize.

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Nonetheless, some researchers argue that the dodo-bird verdict is far from settled. They concede that no established form of treatment has an advantage when it comes to mildly depressed adults, and they agree that in such cases any intervention at all seems to work better than no intervention. But that doesn't mean that all treatments are the same in every case. Cognitive-behavioral therapy, for example, may be particularly well-suited to patients suffering from panic disorder. Exposure-based therapies seem to work best for post-traumatic stress disorder.

The debate has played out in duelling studies over the past 35 years. But the question of whether the dodo really has wings will soon be even more important for Americans. As part of the health care reform act passed last year, psychological treatment will be more accessible to more people, and patients and insurers will demand to know how best to spend their money and time. Should the dodo verdict be overturned?

The notion that no therapy is better than any other originated in the 1930s with psychologist Saul Rosenzweig, then a research associate at the Harvard Psychological Clinic. His ideas on the matter were shaped by an interest in the history of curative techniques, from the kings who applied the healing "royal touch" to the therapeutic spinning chair proposed by Erasmus Darwin and the theories of Sigmund Freud. Rosenzweig thought that all these healers and treatments (which he had memorialized in a peculiar wall-hanging displayed in his office) had a similar way of working on the minds of patients—they used drama and ritual to effectuate a cure. If that approach worked for hundreds or thousands of years of human history, he reasoned, why should contemporary mind-based therapies be any different?

In 1936, Rosenzweig proposed a catchall recipe for treatment—any treatment at all—in a famous paper titled "Some Implicit Common Factors in Diverse Methods of Psychotherapy." The ingredients most frequently cited today include the collaborative bond between the patient and therapist, known as the "therapeutic alliance"; the provision of a believable framework that normalizes the patient's distress; and the buoying hope the patient feels once he has embarked on therapy.

Over the years, Rosenzweig's argument has been bolstered by the research literature. An important paper from 2002 gathered together 17 prior studies of the relative merits of various psychotherapies, mostly for depression. The authors found that the treatments—which included cognitive-behavioral, psychodynamic, and systematic desensitization therapy—showed few differences in terms of outcome, and concluded that the dodo-bird verdict is "alive and well—mostly." The caveat refers to a few data points suggesting that short-term psychodynamic treatment—which focuses on how past experiences affect your present-day life—doesn't work as well as cognitive-behavioral therapy. Similar surveys (here, here, and here) have supported the dodo-bird verdict with fewer qualifications.