Ruiz Vegas, Francisco JavierPeña Vargas, AndrésRamírez Riveros, Eduar S.García Martín, María B.García Beltrán, Diana MilenaHenao, Ángela M.Monroy Cifuentes, AndreaSánchez, Pili D.Suárez Falcón, Juan Carlos2024-05-202024-05-2020200033-3204 - eISSN 1939-1536https://doi.org/10.1037/pst0000273https://hdl.handle.net/20.500.14468/12617This parallel randomized controlled trial aimed to evaluate the effect of acceptance and commitment therapy (ACT) focused on disrupting repetitive negative thinking (RNT) versus a waitlist control (WLC) in the treatment of depression and generalized anxiety disorder (GAD). Forty-eight participants with a main diagnosis of depression and/or GAD were allocated by means of simple randomization to a 2-session RNT-focused ACT intervention or to the WLC. The primary outcomes were emotional symptoms as measured by the Depression, Anxiety, and Stress Scales–21. Process outcomes included ACT- and RNT-related measures: general RNT, experiential avoidance, cognitive fusion, values, and generalized pliance. At the 1-month follow-up, linear mixed effects models showed that the intervention was efficacious in reducing emotional symptoms (d = 2.42, 95% confidence interval [1.64, 3.19]), with 94.12% of participants in the RNT-focused ACT condition showing clinically significant change in the Depression, Anxiety, and Stress Scales–21 total scores versus 9.09% in the WLC condition (70% vs. 8% in intention-to-treat analysis). The intervention effects were maintained at the 3-month follow-up. No adverse events were found. A very brief RNT-focused ACT intervention was highly effective in the treatment of depression and GAD. (PsycInfo Database Record (c) 2020 APA, all rights reserved)enAtribución 4.0 Internacionalinfo:eu-repo/semantics/openAccessartículoAcceptance and commitment therapyRelational frame theoryRepetitive negative thinkingDepressionGeneralized anxiety disorder