Mindfulness-Based Cognitive Therapy for Depression is a very interesting new- ish modality for treating chronic depression in adults. It was created by three researchers and clinicians ( Segal , Williams, and Teasdale) who received a grant to develop a treatment to address the high relapse rate among sufferers of depression. According to statistics cited in their book (see resources, below, pg 12), patients with no history of depression had a 22% chance of having another major depressive episode; those with a history of at least 3 depressive episodes face a 67% chance of having another. Depression seems to be "etched in" to a person's psyche/body over time with more experiences, and this proneness to relapse is what MBCT was developed to address.
Essentially, MBCT is an application of Jon Kabat-Zinn's Mindfulness-Based Stress Reduction work at the University of Massachusetts on the use of mindfulness practice (i.e., meditation) with patients suffering from chronic pain. Kabat - Zinn's work shows that for these people who have had little success with conventional pain management, the internal work of mindfulness practice substantially helped in dealing with pain.
So the authors of MBCT worked with Kabat - Zinn in specifying the MBSR for training chronic sufferers of depression in skills that prevent relapse. Their own research shows in people with 3 or more episodes, MBCT cut the relapse rate in half (over the 60 week follow-up period). Apparently, they hit on something.
MBCT consists of a mix of mindfulness practice, of practicing a mere noticing of sensation ( vipassana practice), as well as certain thought-tracking techniques from cognitive therapy. It is taught as an 8 week class that focuses on skill acquisition, rather than on psychotherapy per se . Groups are from 8-12 people, a size that tends to pull away from the tendency for it to become group therapy. It's really about learning and practicing skills.
Is it spiritual? Not explicitly, neither in design or execution. It really is mindfulness applied to healing and not transformation . Kabat - Zinn's research shows that mindfulness practice does have specific health benefits; it does make for a stronger mind and body. In the context of MBSR or MBCT , it may bring someone into a deeper relationship to Spirit (whatever word you wish to use here), but the context is not intended for that and there is no spiritual context given to encourage that insight.
So it's a curious application of age old wisdom to the healing arts. Buddhist teachers that I've known have poo-pooed such modalities as MBCT , as rather shallow, or even making matters worse by making the ego (the false sense of a separate self) more entrenched. And on the other side, medical researchers are showing that it really does have positive health effects. It's where the two traditions--spiritual and medical/healing--are hashing it out most directly these days.
Perhaps what the " medicalization " of mindfulness practice is showing is the limits and strengths of these different approaches to health. This would be Ken Wilber's argument, that in order to experience ultimate reality, you need to be attuned to spiritual dimensions of life--the insubstantiality of ego, the pervasiveness of consciousness, the oneness of essence. But if your goal is more limited, then the results will be more specific and more confined (as with MBCT --the authors make no claim that it will bring one to enlightenment). Or as he has said, "Give unto Freud what is Freud's, and unto Buddha what is Buddha." That strikes me as a very sane way of seeing it.
(Resources: the officialMBCTwebsite ; Jon Kabat - Zinn's dept. at U. Mass, here ; Wikipedia on vipassana , here )