• Mindfulness-based intervention (MBI) raised trait mindfulness in adults with ADHD. • ADHD symptoms, executive dysfunction, and delay aversion decreased after MBI. • Trait mindfulness and executive dysfunction serially mediated therapeutic effect. • Delay aversion was not a mediator when executive dysfunction was considered. • A randomized controlled trial design was employed. In the dual pathway model, executive dysfunction (EDF) and delay aversion (DEL) are key mechanisms underlying ADHD. This study aimed to develop and evaluate a pathway model to elucidate the mediating roles of trait mindfulness (TM), EDF, and DEL in mindfulness-based interventions’ (MBIs) impact on ADHD symptoms. 120 adults (M age =25.11, SD age =5.33) exhibiting elevated ADHD symptoms were randomized into either an 8-week MBI group (n=60) or a waitlist control group (n=60). ADHD symptoms, EDF, DEL, and TM were assessed. Structural equation modeling was used to examine a theoretical pathway model and construct a data-driven model. Compared with the control group, the intervention group exhibited significant reductions in EDF, DEL, and ADHD symptoms and increased TM. Changes in TM and EDF sequentially mediated the effect of MBI on ADHD symptom reduction. Additionally, changes in TM mediated the impact of MBI on DEL reduction. However, DEL reduction did not link to changes in ADHD symptoms when EDF and TM were considered. It empirically indicated that improvement in TM and, subsequently, improvement in EDF are possible therapeutic mechanisms of MBIs on adult ADHD symptoms. While increased TM was associated with DEL reductions, this pathway was insignificantly related to ADHD symptom reduction.

• A single session CBM-I training successfully altered interpretations and emotions. • Negative interpretation inflexibility predicted bias change after positive CBM-I. • Intolerance of uncertainty predicted bias change after positive CBM-I. • The predicted change in interpretations translated into change in anxious emotions. While anxiety-related cognitive bias modification for interpretations (CBM-I) is generally effective in reducing negative interpretation bias and anxiety, individuals differ in the extent to which they benefit from CBM-I. This proof-of-concept study investigated whether interpretation inflexibility and intolerance of uncertainty account for variability in CBM-I’s effects on interpretations. Participants ( N = 274), primarily female students, completed either a positive or a negative online single-session CBM-I training. Interpretation inflexibility and intolerance of uncertainty were measured before training. Interpretations and mood state were measured before and after training. For the positive CBM-I training, higher negative interpretation inflexibility (i.e., reluctance to revise negative interpretations based on positive information) and higher intolerance of uncertainty predicted smaller reductions in negative interpretations. Changes in negative interpretations mediated the relation between these predictors and changes in anxious emotions. These findings offer new insights into the role of intolerance of uncertainty and negative interpretation inflexibility as predictors of CBM-I outcomes and highlight the potential of personalized approaches that match CBM-I training to the specific needs of individuals with anxiety.