The roles of personality traits and close social contact in the expression of momentary borderline personality disorder symptoms in daily life.

Dimensional models of personality, such as the five-factor model (FFM), have demonstrated strong coherence with the presentation of personality disorders, including borderline personality disorder (BPD). Given that select personality trait elevations have been linked to impairments in multiple life domains across diagnostic groups, we sought to replicate findings from a previous investigation of the utility of the FFM in predicting BPD-relevant outcomes (i.e., negative affect intensity and instability, impulsivity, and interpersonal disagreements) in the daily lives of those with BPD (Hepp et al., 2016) and community participants. As interpersonal context is instrumental in determining the strength of effects observed in studies examining individuals with BPD, we utilized ecological momentary assessment across 3 weeks (6 times daily; ntotal = 15,889) to test whether close social contact (CSC) would moderate the effects of personality on momentary outcomes. Overall, results suggest that CSC is an important moderator between the effects of personality and daily life outcomes for individuals with BPD (N = 56), but not for community individuals (N = 60). For individuals with BPD, CSC may function as both a protective buffer and a risk factor, depending on outcome. For example, CSC attenuates experience of negative affect intensity for individuals with elevated neuroticism, but CSC may predict more frequent disagreements for individuals who report lower agreeableness. We replicated approximately half of the original study's findings, and results support that FFM personality is predictive of BPD-relevant outcomes broadly. However, interpersonal context is key to understanding these relationships for individuals with BPD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).