State mindfulness and repetitive thought: A systematic review of experimental and ecological momentary assessment research

Objectives: Although mindfulness training is associated with reductions in trait repetitive thought over time, mindfulness is less well understood as a regulatory strategy for momentary (state) repetitive thought. This review examined evidence for a theoretically-predicted inverse momentary association between mindfulness and repetitive thought.Methods: A systematic search of PubMed, PsycInfo, and Web of Science was conducted on August 1, 2024 to identify studies that 1) used an experimental induction or momentary assessment design; 2) reported an association between facets of mindfulness and repetitive thought; and 3) were published in English. Data extraction and methodological quality assessment used a standardized codebook and data were synthesized narratively. Results: Forty eligible studies were identified and grouped by methodology: experimental induction (k = 17), ecological momentary assessment (EMA; k = 12), ecological momentary intervention (EMI; k = 3), and daily diary (k = 8). Almost all studies used adult samples, including clinical, elevated symptom, and non-clinical samples. Most EMA studies found the predicted inverse association between state mindfulness and repetitive thought with small to medium effect sizes. Findings from experimental and daily diary studies were more mixed. Discussion: Despite theoretical predictions of a strong and consistent inverse association between mindfulness and repetitive thought, observed patterns varied by methodology and facet of mindfulness. Although methodological heterogeneity and psychometric quality issues indicate the importance of standardized assessments in future research, the present review suggests that mindful awareness may be a mechanism by which mindfulness regulates repetitive thought.