Does one form of psychotherapy work better than another?
Adherents to particular schools of therapy hate the dodo verdict, of course. Most ruffled are the cognitive-behaviorists, who have long taken pride in their rigorously tested, standardized methods. Indeed, there have been many randomized, controlled trials showing that cognitive-behavioral therapy is more effective for anxiety and depression than placebos, and that it compares favorably with antidepressants. These results are not contested. But they don't disprove the dodo-bird verdict, since other forms of therapy might be just as good.
Dodo deniers hold that various psychotherapeutic treatments might happen to produce similar improvements in clinical trials, but that's not because they're doing the same thing. Rather, different mechanisms of action end up moving patients roughly equal distances toward recovery. To support this idea, they point to studies demonstrating that the therapeutic alliance, supposedly one of the key factors common to all therapies, has only a moderate impact on treatment outcome: Even if patients report an extremely strong bond with their therapist, this is not enough to guarantee that they will improve .
The deniers also cite research showing that some forms of treatment seem to work better than others for specific disorders. A pair of studies from the mid-1990s found that patients with panic disorder benefited more from cognitive-behavioral therapy than something called "applied relaxation therapy." (The creator of applied relaxation published his own data suggesting otherwise.) Meanwhile, patients with PTSD may do better when they're asked to confront traumatic memories, rather than learn anxiety-management strategies. (A caveat: More of the patients in the anxiety-management group dropped out of the program, which may have skewed the results.)
Another line of argumentation from dodo opponents is that the survey studies, which are the basis of the dodo-bird verdict, commit various methodological errors. For instance, they lean heavily on particular disorders, such as adult depression and anxiety, and have few or no examples of other types of patients, such as people with psychosis and children. They also tend to focus on familiar treatments, such as cognitive-behavioral therapy and psychodynamic therapy, instead of testing the full range available. As such, they don't give a fair appraisal of how psychotherapies stack up across the board.
On top of all this, the debate has been muddied by the slippery question of therapist ability. Better, more-experienced practitioners achieve better results—that much seems clear. But there have been few studies of how the skills of a given therapist affect the outcome of treatment. Even defining those qualities that make for a better therapist can be complicated. One study looked at data from a major NIH depression trial and concluded that the better therapists weren't the ones who had more experience but those who would rather talk to their patients than prescribe medication and who expected talk-therapy to take a long time.
For now many researchers are sidestepping the dodo debate altogether. Instead of trying to figure out whether one therapy is more effective than another, they're looking for simple ways to make all therapies work better. Certain factors that have little to do with the theoretical foundation of a treatment could make a huge difference. The therapist's ability to form a strong bond with the client, for example, and the manner in which he or she gives instructions to patients, would both affect the outcome of any intervention. Some research has explored patient characteristics and showed that people who tend to balk at requests and are easily provoked respond better to therapists who allow them to take the lead in conversation. This may seem obvious, but it held true irrespective of the therapist's theoretical perspective and again suggests that all treatments could be tweaked to boost their impact.
Patients and insurers might still wonder whether the dodo should be extinct, and if it matters what treatment someone gets. There's at least one study under way, of panic disorder, which hopes to confirm or deny the classic verdict. It is led by University of Pennsylvania and Cornell researchers from both the psychodynamic and cognitive-behavioral schools, and it compares the two treatments in a population of around 200 people who suffer panic attacks. The idea is to have any bias cancel out, while ensuring that patients in both treatment groups receive high-quality care. It's not clear whether the study will save the dodo or finally kill it off. At the very least, we'll know a little more.
Alastair Gee is a San Francisco-based journalist and has written for the Economist, the New York Times, and the Lancet.
Drawing of a dodo bird by Photos.com/Thinkstock .