Process-Based Psychological Flexibility in Migraine: Cross-Sectional Associations and Exploratory Idiographic EMA Findings

Background Migraine care often relies on aggregate symptom scores, while clinicians must make decisions with individuals whose process dynamics may not follow group averages. We therefore examined whether trait-level and behavior-level indicators of psychological flexibility were related to headache burden and quality of life, and whether these between-person patterns aligned with within-person EMA dynamics. Methods Participants with self-reported migraine completed the Multidimensional Psychological Flexibility Inventory (MPFI), the Process-Based Assessment Tool (PBAT), HIT-6, the Pain Catastrophizing Scale (PCS), the Pain Acceptance Questionnaire (QPAC), and the Satisfaction with Life Scale (SWLS). Principal component analysis identified two HIT-6 dimensions. We then combined multivariable regression and feature-selection models to evaluate associations between process variables, headache burden, and quality-of-life outcomes. In a separate ecological momentary assessment (EMA) dataset, two eligible participant cases were examined using lagged process models, with one case visualized in the main text. Results The HIT-6 was better represented as two related dimensions, symptom burden and functional interference. Across cross-sectional models, higher inflexibility and lower acceptance were associated with poorer outcomes, and PBAT indicators linked to attentional drift, cognitive fusion, and disengagement from valued action showed recurrent predictive relevance. In the EMA analyses (two eligible cases), lagged associations showed person-specific feedback patterns that only partly overlapped with between-person findings, including a reciprocal attention-connection loop in one case. Conclusion The findings support a process-based account of migraine impact in which inflexibility-related processes are relevant to functioning. At the same time, the EMA results indicate that processes differentiating people are not automatically the same processes that organize short-term change within a given person. Integrating trait and EMA assessment may strengthen ACT-informed case formulation and treatment planning by improving target prioritization and sequencing. Trial registration Not applicable.