RESUMEN
The current prospective longitudinal study evaluated brooding rumination as an intervening mechanism of the association between COVID-19-related stress and internalizing symptoms during the first year of the pandemic. Attention-deficit/hyperactivity disorder (ADHD) status and adolescent sex were tested as moderators of the indirect effect. Adolescents with and without ADHD (N = 238; M age = 16.74) completed rating scales of COVID-19 stress and both adolescents and parents completed ratings scales of internalizing symptoms in May/June 2020 (T1). In October/November 2020 (T2), adolescents reported on their brooding rumination. Adolescents and parents reported on internalizing symptoms again in March/April 2021 (T3). Covariates included participant characteristics and baseline symptoms. T1 self-reported COVID-19-related stress was associated with increased T3 self-reported anxiety (ab = 0.10), self-reported depression (ab = 0.07), and parent-reported depression (ab = 0.09) via T2 brooding rumination. The indirect effect did not differ for adolescents with and without ADHD or for female and male adolescents. Brooding rumination may be one mechanism to target to promote the mental health adjustment of adolescents during periods of high stress of the COVID-19 pandemic and future stressors.