Are some psychotherapies more effective than others? – Or are we being swamped by an ever-growing list of bland interventions that claim to be the latest advances in psychotherapy, but are simply no better or no worse than what has gone before?
Around 30 years ago, a number of influential studies all suggested that although psychotherapies were more effective in treating mental health problems than placebos and other appropriate controls, no psychotherapy was more effective than any other psychotherapy (e.g. Smith, Glass & Miller, 1980). As early as 1936 Saul Rosenzweig had labeled this effect the Dodo Bird Verdict (Rosenzweig, 1936) after the bird in Lewis Carroll’s “Alice’s Adventures in Wonderland”. In that story, a number of animals had become wet and in order to dry themselves ran round the lake to see who could get dry first. No one measured how far they’d run or for how long, but when asked who had won, the Dodo bird said “Everybody has won and all must have prizes”!
Those who agree with the Dodo bird verdict claim that all psychotherapies are equally effective because they all contain some important common factors that are shared across all psychotherapeutic interventions. This is known as the common factors theory, and Grencavage & Norcross (1990) identified up to 35 common factors across psychotherapies that influence therapeutic outcome. They divided these into five main groups that included client characteristics, therapist characteristics, the change process, treatment structures, and therapist-client relationship elements.
One of the most important common factors affecting outcome is the therapist-client relationship – known as the therapeutic alliance (Del Re, Flückiger, Horvath, Symonds & Wampold, 2012), and Wamphold, Minami, Baskin & Tierney (2002) found that seven percent of the variability in treatment outcome was due to the therapeutic alliance compared with only one percent attributable to the principles inherent in the type of psychotherapy being deployed! Apart from the therapeutic alliance itself, specific features of the therapist have also been identified as contributing to the success of therapy. These include positive, warm, and caring attitudes towards the client, and providing good feedback, helping the client to focus on and understand their own thoughts, attempting to promote autonomy and self-efficacy in their clients, and helping the client with their existing relationships.
However, there is evidence that can be mustered on both sides of the Dodo Bird Verdict, and this debate is still very much alive (Wampold, Imel & Miller, 2009; Siev & Chambless, 2009). Some claim that improvements in statistical analyses now allow us to make fine-grained distinctions between the effectiveness of different therapies in a way that we could not do previously (Otte, 2011); We can demonstrate that some psychotherapies are more effective for some mental health problems than for others; and indeed, we not only have to consider whether interventions are effective in treating psychopathology symptoms, we also have to consider whether they might also be harmful in the sense that they may evoke negative responses to treatment in some clients or client groups (e.g. individuals diagnosed with substance dependency) (Dimidjian & Hollon, 2010). Indeed, a recent paper has even suggested that mindfulness-based approaches might even be detrimental to some client groups
So, while there is still lively debate about the relative efficacy of various interventions for psychopathology, there is no doubt that hundreds of studies have clearly demonstrated that psychotherapy is effective. The Dodo Bird Verdict has also helped to focus attention on those aspects of psychotherapy that are common across a majority of intervention types (e.g. therapist characteristics, the therapeutic alliance, etc.), and clinical psychologists are currently working to identify some of the important characteristics that make some psychotherapists more effective than others (http://www.apa.org/monitor/2013/02/therapist.aspx).