[Note: This is a slightly revised version of a previous post with the same title.]

Unless I want to spend the next decade on this project, I won’t be going into a lot of detail about each study that addresses the benefits of mindfulness. Let’s just look at a couple meta-analyses. One, “Mindfulness-based therapy: A comprehensive meta-analysis “(2013), concludes that mindfulness-based therapies are “an effective treatment for a variety of psychological problems”, but the authors also note that the moderate effectiveness of MBT “did not differ from traditional CBT [Cognitive-Behavioral Therapy] or behavioral therapies … or pharmacological treatments.”

The other meta-analysis was “The effect of mindfulness-based therapy on anxiety and depression: A meta-analytic review” (2010), which analyzed 39 studies (out of 727 originally identified as possible candidates for review). The authors found that mindfulness-based treatments were moderately effective for anxiety and depression, with stronger effects for individuals with anxiety and mood disorders. But their meta-analysis included many non-controlled studies, so how can we interpret these results?

Looking more closely at the 39 studies, 23 had no control or comparison group, 16 included a control or comparison group, of which 8 were waitlist controls, 3 were treatment-as-usual (TAU), and 5 actually had an active comparison treatment. So that’s 5 out of 39 MBT studies with a decent control group. But wait: of the 5 studies that were described as having “active controls”, two were “education programs” and two were types of art therapy. Education programs and art therapy are insufficient comparison treatments because they do not match the main intervention in common factors of efficacious treatments or placebo effects. (Note: I have designed such comparison interventions, so know a bit whereof I speak). Only one of the 5 studies listed as having an active control condition could be called an empirically supported “real” intervention – and that was cognitive-behavior group therapy, a condition with a grand total of 18 participants, representing just 1.5% of the 1,140 participants covered in the meta-analysis.

The authors of the 2010 meta-analysis actually criticize an earlier meta-analysis on the effect of mindfulness-based treatments partly because the authors of the earlier meta-analysis only reviewed controlled studies – and the other meta-analysis concluded that MBT does not have reliable effects on anxiety and depression.   To quote: “Our study suggests that this conclusion was premature and unsubstantiated. The authors included only controlled studies, thereby excluding a substantial portion of the MBT research.”

Well, yeah, that is a legitimate problem. I’d recommend more high-quality controlled studies to address it. Then do another meta-analysis.

The problem with the research record on mindfulness is the same problem that plagues a lot of psychotherapy research: experimenter bias, which can taint even controlled studies. James Coyne puts this point beautifully in Salvaging Psychotherapy Research: a Manifesto:

“The typical RCT [Randomized Controlled Trials] is a small, methodologically flawed study conducted by investigators with strong allegiances to one of the treatments being evaluated. Which treatment is preferred by investigators is a better predictor of the outcome of the trial than the specific treatment being evaluated….

Overall, meta-analyses too heavily depend on underpowered, flawed studies conducted by investigators with strong allegiances to a particular treatment or to finding that psychotherapy is in general efficacious. When controls are introduced for risk of bias or investigator allegiance, effects greatly diminish or even disappear.”

So, where does that leave us? With the need to do more, better research on mindfulness-based treatments. In the meantime, it’s probably safe to say that mindfulness practice and mindfulness-based treatments are helpful in some ways, for some people – but a lot of questions remain unanswered. To the degree that mindfulness advocates present evidence about the wonderful effects of mindfulness as unequivocal and/or uncontested (much less “staggering”, as per Kabat-Zinn), they are exaggerating and overstating their case.

And that’s it for third corner of the ideological square: Emphasize Our good things – the idea being unquestionable evidence of unmitigated goodness. On to the last corner: De-emphasize Their good things.

Reference: Jon Kabat-Zinn Full Catastrophe Living: Using the Wisdom of Your Body and Mind to Face Stress, Pain, and Illness, Kindle Version, Revised Edition 2013; Bantam Books, New York