Practice matters: The role of mindfulness skills in emotion dysregulation in borderline personality disorder

Mindfulness skills training constitute a core element of dialectical behavior therapy (DBT) that has been proposed as a key component to improve emotion dysregulation (ED) in borderline personality disorder (BPD). However, the relationship between the time spent practicing mindfulness skills at home and changes in ED is not well-understood. This study aimed to determine whether daily mindfulness practice meaningfully improves ED, and, if so, the minimum dose needed to do so. A total of 75 BPD outpatients participated in a 10-week DBT mindfulness skill training program. We systematically tracked the participants' mindfulness practice and their ED levels throughout the sessions. A total of 499 observations were recorded. We used multilevel modeling with a time-lagged approach to investigate the association between weekly practice and ED over time. Greater mindfulness practice predicted improvements in ED in the following week. A bidirectional relationship was also found; a higher level of ED impaired subsequent mindfulness practice. When accounting for the previous week's ED level, participants who practiced ≥3 days and >30 min per week experienced a statistically significant decrease in ED compared to those who did not engage in regular practice. These results highlight the key role of mindfulness practice as a behavioral component to improve emotion regulation in individuals with BPD. These findings suggest that therapists should inform patients about the minimum dose of mindfulness practice needed to improve emotion regulation in order to adjust expectations and improve treatment outcomes.