Depression is a major public health problem that, like other chronic conditions, tends to run a relapsing and recurrent course [1
], producing substantial decrements in health and well-being [2
]. WHO predicts that by 2020 depression will be the second leading cause of disability in the world [3
]. The current cost of mood disorders in the UK has been calculated at 1.5% of GDP [4
] and a recent King's Fund report projects that the cost will be £12.15 billion by 2026 [5
]. More than 50% of patients experience at least 2 episodes of depression. Moreover, without ongoing treatment people suffering recurrent depression suffer relapse/recurrence at rates as high as 80%, even after successful acute treatment [6
]. Thus, most of the prevalence, burden and cost of depression is a consequence of relapse/recurrence and the majority of the burden attributable to depression could be offset through interventions aimed at the prevention of depressive relapse/recurrence [8
]. Currently the majority of depression is treated in primary care, and m-ADM is the mainstay approach to preventing relapse/recurrence [9
]. To stay well NICE recommends that people with a history of recurrent depression continue m-ADM for at least two years [11
]. However, many patients experience unpleasant side-effects, rates of ADM adherence tend to be low, and many patients express a preference for psychosocial interventions [12
]. Service user organisations therefore advocate greater availability of psychosocial therapies. Similarly, the King's Fund recommends: "expansion of evidence-based interventions in primary care" and "more research into the cost-effectiveness of a range of interventions, including mental health promotion and prevention initiatives" [[5
]; p. xxi]. In line with this, significant government initiatives such as the Improving Access to Psychological Therapies programme are beginning to explore accessible, acceptable and cost-effective psychosocial models of care and envisage up to 250 centres offering psychosocial treatments within a decade [4
Psychosocial approaches to prevent depressive relapse/recurrence
While there is a strong evidence base for psychosocial treatment of current depression, only more recently has attention turned to preventing depressive relapse/recurrence. Policy initiatives, user group and professional consensus recommend as priorities for future research the development of psychosocial interventions to prevent depressive relapse/recurrence and the use of non-traditional delivery systems, such as group interventions, to maximise accessibility and cost-effectiveness [15
]. MBCT is a psychosocial group-based relapse prevention programme. It was developed from translational research into mechanisms of depressive relapse/recurrence [17
]. There is much clinical enthusiasm for MBCT, as evidenced by high rates of patient engagement and the recent establishment of MBCT therapist training programmes in the UK at the Universities of Bangor, Exeter and Oxford. In summary, MBCT shows the potential to contribute significantly to reducing the prevalence of depression in UK primary care settings.
Secondary research findings
Narrative reviews of the broad class of mindfulness-based approaches suggest that they produce substantial improvements on measures of depressive symptoms compared with control groups: Cohen's d (or standardised mean difference) = .86, SD = .3 [18
]; Cohen's d = .54, 95% CI .39-.68 [19
]. Two uncontrolled trials of patients with a history of recurrent depression and high levels of residual symptoms demonstrate improvements in depressive symptoms, with many people in remission at follow up [20
]. The two most significant well controlled MBCT randomised controlled trials to date found that MBCT plus usual care halved rates of relapse compared to usual care alone, over sixty weeks of follow-up [22
]. However, both trials excluded people receiving the current treatment of choice (m-ADM), did not compare MBCT with another active treatment, were not based in real world healthcare settings, had relatively short follow-ups, and did not speak to MBCT's mechanism of change. A recent systematic review of the few existing MBCT controlled trials for depression (including these 2 randomised controlled trials) suggests a significant additive effect of MBCT over usual care for patients with recurrent depression, but only for patients who have experienced three or more previous episodes [24
]. However, the authors of this review found no trials comparing MBCT with an active treatment, and suggest this as the next step. Moreover, they found no evidence of the "specific effectiveness of MBCT, despite this being the logical progression from the current research." That is to say, no trials speak to whether MBCT works through its specific hypothesised mechanisms and/or through non-specific cognitive-behavioural, psycho-education and group/therapist support components. They suggest "the need for randomised controlled trials to compare MBCT with other non-pharmacological approaches" and that include tests of the specific and non-specific mechanisms of change [24
]. A key issue that the current literature leaves unresolved is whether the robustly demonstrated relapse prevention effects of MBCT are due to the hypothesized mechanism of change, the cultivation of mindfulness skills.
Our exploratory trial
In our exploratory trial 123 patients with recurrent depression on m-ADM were randomised to either continued m-ADM or MBCT plus m-ADM tapering/discontinuation [25
]. The findings suggest that MBCT may not only provide an alternative to m-ADM (relapses at 15 months: MBCT 47% vs
. m-ADM 60%), but that in an adequately powered definitive phase III trial it may produce superior outcomes. The study suggested that MBCT was also superior to m-ADM in terms of improved quality of life, reduced residual depressive symptoms, and reduced psychiatric co-morbidity. Finally, a secondary qualitative study suggested several putative mechanisms of action [26
Why is this trial needed now?
First, we have sufficient evidence from existing trials and our exploratory trial to progress to the next stage of the treatment development process: a definitive randomised controlled trial. That is to say, there is preliminary evidence suggesting that MBCT has potential to significantly reduce the prevalence of depression and to do so cost-effectively. Second, in the UK the vast majority of depression presents in primary care, yet the studies reviewed above do not speak to the generalisability of MBCT to real world primary care settings. Third, the randomised controlled trials to date [22
] were conducted by the group that developed MBCT and an independent replication is needed. Fourth, depression relapse prevention trials are needed that use a more sophisticated and patient-centered approach to outcome assessment that extends beyond 1-year follow-up and assesses patient-centred secondary outcomes [27
]. Fifth, none of the research to date speaks to whether MBCT is efficacious through its hypothesised mechanism of action. Such mechanisms research informs theory and treatment and may produce a simpler and more cost-effective approach to relapse prevention. Finally, the ISRCTN Register (June, 2008) records no comparable recent or ongoing trials in the UK. No current trials of recurrent depression speak to mechanisms of change.