Updated: Mar 31, 2020
You may have heard someone refer to “evidence-based” therapies and wondered what this means and whether it points to some therapies being "better" than others. Here I want to explain what is meant by “evidence-based;” which therapies this may be referring to; and what this means for deciding what is “better” or best for clients.
For starters, about "evidence": It’s important to know that “evidence-based” refers to a therapy's effectiveness based on a certain kind of evidence. That evidence is derived from scientific methods that yield quantitative results, i.e., results based on comparing outcomes of various approaches that are representable in numbers that are larger or smaller in size than each other. There are, however, other kinds of evidence—intuitive, subjective belief, anecdotal, spiritual. Thus, the "evidence" we are talking about is actually narrow in scope, even if it carries a lot of authority in our culture. We should remember that the kind of the evidence we rely on affects what it can tell us. Quantitative evidence can shows that a particular technique reduces certain symptoms as compared to others. But that same evidence does not tell us what significance the reduction in that symptom had for the client—e.g., whether it means they feel more existentially connected or whether the change in symptom also translates into change in character or shift in personality structure.
What a study is looking at also effects how we should understand "evidence." Based on quantitative evidence, we might say that one therapeutic method is better at treating depression because a study showed that those treated for six months with one method had diminished symptoms compared to those treated by a different method. Another study may track whether those symptoms continue to be diminished after a certain period. That study may show that, while one method helped diminish symptoms, the symptoms returned more quickly than the other method. The two studies were both valid, but their variables were different. Thus, we can see that "evidence" reflects a certain set of assumptions and variables; and that if you change those assumptions and variables, the evidence might show something different.
For many years, “evidence-based” therapy was almost synonymous with Cognitive Behavior Therapy (CBT) and related top-down approaches. There were too few studies on other methods to show they were effective. Or quantitative studies ostensibly discredited certain approaches, ranging from healing touch to dream analysis and behavioral therapies for certain disorders. In the past decades, it has been more common to expand what “evidence-based” therapies include. They now include a range of other approaches, from Dialectical Behavioral Therapy (DBT) to Mentalization Based Treatment (MBT) and Acceptance and Commitment Therapy (ACT), among others. There were fewer studies until recently showing that psychodynamic therapies (PDT) were effective, i.e., those therapies that focus on how conflict among conscious and unconscious forces—often related to attachment patterns and adaptions in early childhood to one's caregivers—determines one’s current experience and the degree to which one could have meaningful relationships and respond flexibly in adulthood. These therapies are usually relational rather than cognitive. They seek to uncover and resolve conflicts through the immediate relationship with the therapist.
Things have changed in recent years. First, it has been repeatedly shown that the effectiveness of therapy is significantly related to the skill of the therapist and their capacity to attune to the client or patient as well as the particular theory or technique they use. Further, many studies have now shown that PDT is as effective in the treatment of various conditions as are CBT and other cognitive approaches, including depression, anxiety, personality disorders, addiction, and relationship distress. Again, it's important to look at which variables are being measured in these studies, including the length of therapy, whether therapy included the conjunctive use of pharmaceuticals, and whether studies measured remission rates—i.e., how long after therapy ended that the effects could still be seen.
How should all this inform our decision to do therapy or which therapy to choose? The answer is clearly very individual. Having objective evidence supporting a certain therapy may help you have more faith in it and thus be more motivated and engaged. Alternatively, you may decide that your subjective experience with the method and the particular therapist is more important. Or you may decide that symptom reduction is only part of your goal, and that individuation or understanding how to be more authentic and connected to your values is just as as important. Thus, the significance of “evidence-based” therapy depends greatly on one’s own values and reasons for seeking change. A so-called “discredited” therapy may have a powerful and useful effect on one’s subjective experience. Or the particular therapeutic theory may be less significant to healing than the relationship with the therapist. It remains part of a client’s reflection and conversation with their therapist what significance evidence has and which evidence they want to rely on in their own process.