Recently, there has been an increased
interest in studying the effects of mindfulness-based interventions for
people with psychological and physical problems. However, the mechanisms of
action in these interventions that lead to beneficial physical and
psychological outcomes have yet to be clearly identified.
The aim of this paper is to review,
systematically, the evidence to date on the mechanisms of action in
mindfulness interventions in populations with physical and/or psychological
Searches of seven databases (PsycINFO,
Medline (Ovid), Cochrane Central Register of Controlled Trials, EMBASE,
CINAHL, AMED, ClinicalTrials.gov) were undertaken in June 2014 and July 2015.
We evaluated to what extent the studies we identified met the criteria
suggested by Kazdin for establishing mechanisms of action within a
psychological treatment (2007, 2009).
We identified four trials examining mechanisms
of mindfulness interventions in those with comorbid psychological and
physical health problems and 14 in those with psychological conditions. These
studies examined a diverse range of potential mechanisms, including
mindfulness and rumination. Of these candidate mechanisms, the most
consistent finding was that greater self-reported change in mindfulness
mediated superior clinical outcomes. However, very few studies fully met the
Kazdin criteria for examining treatment mechanisms.
There was evidence that global
changes in mindfulness are linked to better outcomes. This evidence pertained
more to interventions targeting psychological rather than physical health
conditions. While there is promising evidence that MBCT/MBSR intervention effects
are mediated by hypothesised mechanisms, there is a lack of methodological
rigour in the field of testing mechanisms of action for both MBCT and MBSR,
which precludes definitive conclusions.