Beyond Mindfulness Assessed by Questionnaires: The Mindful-Breathing Exercise as an Additional Approach in PTSD and Depression

Objectives Despite various methodological concerns, previous studies mainly use questionnaires to assess mindfulness. Following a multi-measurement approach, the present study aimed to evaluate the added value of an experience-sampling measure in the context of posttraumatic stress disorder (PTSD) and depression. Method Data were collected in a PTSD group, depression group, and control group (each n = 33). The Mindful-Breathing Exercise (MBE) was used as an experience-sampling method and the Five Facet Mindfulness Questionnaire (FFMQ) as a mindfulness questionnaire. Clinical variables included PTSD and depressive symptoms. Results Scores from the MBE and the FFMQ were positively correlated in the control group ( r = 0.48) and the depression group ( r = 0.28), while a non-significant correlation emerged for the PTSD group. On the level of FFMQ facets, results were heterogeneous among the three groups. The MBE predicted hyperarousal ( β = − 0.41) and intrusions ( β = − 0.32) in the PTSD group, whereas the FFMQ predicted depressive symptoms in the depression group ( β = − 0.41) and the control group ( β = − 0.65). Compared to the control group, the PTSD group ( d = 1.88) and the depression group ( d = 1.67) demonstrated lower FFMQ scores. In terms of the MBE, there was a trend towards higher scores in the control group than either clinical group. Conclusions Findings hint at conceptual overlaps and distinctive features of both measurement approaches. With respect to the clinical context, results suggest an added value of the MBE to questionnaire-based assessments of mindfulness with respect to its predictive value for hyperarousal and intrusions. Preregistration This study is not pre-registered.