Two components of psychological flexibility and their role in mental health: Validation of the Dutch Multidimensional Psychological Flexibility Inventory (MPFI-60 and MPFI-24)

Psychological flexibility, the capacity to remain open, present, and value-driven even in the face of distress, is increasingly recognized as a key determinant of mental health. The aim of this study was to validate the Dutch translations of the Multidimensional Psychological Flexibility Inventory (MPFI-60) and its short form (MPFI-24) and to examine the prospective relation with mental health. A community sample of Dutch-speaking adults (N=832; mean age: 55(SD:13)) completed self-report measures on psychological flexibility and mental health. Confirmatory factor analyses supported a two-factor second-order model representing psychological flexibility and inflexibility, providing good fit for the full and short version. Internal consistency across all subscales of both instruments was good. Hierarchical regression analyses demonstrated that psychological flexibility and inflexibility were prospectively associated with well-being and mental health complaints, respectively. However, when both constructs were included in the regression models, only psychological inflexibility emerged as a significant predictor of mental health complaints, including depression, anxiety and stress. This has important implications for future research. The findings also support the use of the Dutch MPFI as a valuable tool for assessing psychological flexibility and psychological inflexibility, with the shorter MPFI-24 offering a more practical and efficient alternative in both clinical practice and research.