An Investigation of the Interaction of Trait Repetitive Negative Thinking and Neuroticism on Default Mode Network Activity During Negative Self-Referential Processing: a Cross-Sectional fMRI Study

Repetitive negative thinking (RNT) and neuroticism are two of the most prominent transdiagnostic risk factors for internalizing disorders. Previous research highlighted a complex relationship between neuroticism and RNT. However, no study has yet examined their interaction at the neural level. Since RNT is predominantly linked to increased recruitment of the default mode network (DMN), we hypothesized that neuroticism might amplify this association. Since the salience network is known to modulate DMN recruitment, the anterior insula was investigated exploratorily. Trait RNT and neuroticism were assessed in a sample of 126 healthy participants, followed by a functional magnetic resonance imaging task designed to elicit negative self-referential processing. Linear models were employed to examine the interaction between trait RNT and neuroticism to predict brain changes, as well as the main effects of RNT, while controlling for the effects of age and sex.No significant interaction between trait RNT and neuroticism in relation to DMN and AI recruitment was found. However, a positive association emerged between trait RNT and recruitment of the precuneus, during negative self-referential processing compared to distraction. Moreover, responses of the anterior insula were inversely related to trait RNT. Our results not only confirm previous findings of DMN recruitment as a biomarker of trait RNT, but also underscore the potential utility of anterior insula activity during negative self-referential processing as a protective biomarker against RNT. The absence of a significant interaction between RNT and neuroticism may suggest that an alternative conceptualization of their relationship could better capture their underlying dynamics.