This Lancet article uses the same approach and finds the same results as Soul 2 Sole

Mindful meditation developed to recognize and respond constructively to the thoughts and feelings associated with depression relapse, thereby preventing a downward spiral into depression.  It is often considered a more spiritual approach than traditional cognitive therapy because it employs meditation-based practices to teach clients how to step outside of their emotional experiences, observe their circumstances in non-judgmental fashion and, as a result, respond more proactively (rather than reactively) to stressful circumstances.

http://www.patheos.com/blogs/faithonthecouch/2015/04/spiritually-integrated-psychotherapy-as-effective-as-meds-for-longterm-relief-from-depression-says-lancet/