More benefits than costs: Associations of co-rumination with positive friendship quality and depressive symptoms at the within-person level.

Co-rumination, or excessive problem talk within a dyadic relationship, has been suggested to have both costs and benefits; it has been associated with both increased depressive symptoms and higher friendship quality. Although previous research has shown moderate concurrent and longitudinal associations between co-rumination, depressive symptoms, and friendship quality, it is unclear whether these processes also take place at the within-person level (i.e., whether increases in co-rumination co-occur with or predict increases in depressive symptoms or friendship quality). Furthermore, some of co-rumination's effect on depressive symptoms may be suppressed due to an indirect effect through friendship quality. The present study aimed to test the concurrent and longitudinal associations between co-rumination, depressive symptoms, and positive friendship quality at the within-person level in a longitudinal four-wave study of early and late adolescents. Participants were younger (M_age = 11.58, 49.5% boys) and older (M_age = 17.79, 24.5% boys) Dutch adolescents (N = 510) who reported on their co-rumination and relationship quality of their closest friendship, as well as their depressive symptoms. Results revealed that adolescents who generally experienced more co-rumination also experienced more depressive symptoms and more positive friendship quality (between-person results). At the within-person level, however, co-rumination was only concurrently associated with friendship quality and not with depressive symptoms, and no predictive effects were found. This suggests that the theorized costs and benefits of co-rumination only take place at the between-person level and may not reflect intraindividual processes. As such, co-rumination may provide more benefits than costs. (PsycInfo Database Record (c) 2025 APA, all rights reserved).