Borderline personality disorder (BPD) features have been linked to deficits in mindfulness, or nonjudgmental attention to present-moment stimuli. However, no previous work has examined the role of fluctuations in mindfulness over time in predicting BPD features. The present study examines the impact of both between-person differences and within-person changes in mindfulness. 40 women recruited to achieve a flat distribution of BPD features completed 4 weekly assessments of mindfulness (Five Facet Mindfulness Questionnaire; FFMQ) and BPD features. Multilevel models predicted each outcome from both 1) a person’s average levels of each facet and 2) weekly deviations from a person’s average for each facet. Average acting with awareness, nonjudging, and nonreactivity predicted lower BPD features at the between-person level, and weekly deviations above one’s average (i.e., higher-than-usual) nonjudging predicted lower BPD feature expression at the within-person level. Within-person fluctuations in the nonjudging facet of mindfulness may be relevant to the daily expression of BPD features over and above dispositional mindfulness.
