Thesis defense Marleen ter Avest (Donders series 512)

21 September 2021

Promotors: prof. dr. A.E.M Speckens, prof. dr. P. Spinhoven
Copromotors: dr. C.U. Greven,  dr. M.J. Huijbers

Mindfulness-Based Interventions for Depression: How does it work and for whom?

The overall aim of this thesis was to investigate how Mindfulness-Based Cognitive Therapy (MBCT) and Mindfulness-Based Compasssionate Living (MBCL) work in individuals with recurrent depression by investigating the course and possible interplay of mindfulness/self-compassion and affect during MBCT/MBCL. Moreover, the course and possible interplay between mindfulness practices and depressive symptoms during and after MBCT was investigated. Given that most previous research into the possible working mechanisms is based on correlational research and on short term-outcome, the current thesis endeavors to further develop this field by including multiple measurements on both short- and long-term outcomes, and by applying autoregressive-latent trajectory (ALT) modeling.
In addition, this thesis aimed to shed further light on the heterogeneity of individuals with depression by meeting the need for more sophisticated examination of possible moderators. The QUalitative INteraction Trees (QUINT) method was applied, which focuses on identifying qualitative treatment-subgroup interactions, considers higher order interaction effects and allows for non-linear relationships. It identifies subgroups of patients in which one treatment is more beneficial than another, and for whom the reverse holds true.
Results from the current thesis suggests that increases in positive affect play a more prominent role in MBCT for depression, while this is the case for decreases in negative affect in MBCL for depression which is preceded by increases in self-compassion. Moreover, depressive symptomatology might act as a barrier to carry out mindfulness practices. Lastly, MBCT in addition to treatment-as-usual may be more beneficial for those who ruminate more and had their first depressive episode at an earlier age and for those with lower levels of quality of life. These findings may lead to further refinement of MBCT/MBCL and targeting of MBCT in individuals with recurrent depression.