Neurobiological Mechanisms of Pathological Rumination and Effects of Aripiprazole

Summary

This randomized, single-blind (assessor-blind) controlled trial aims to investigate the efficacy of aripiprazole as an augmentation strategy for treating pathological rumination in patients with major depressive disorder (MDD). Pathological rumination-defined as repetitive, intrusive, and uncontrollable negative thinking-has been identified as a major transdiagnostic risk factor for the development, maintenance, and recurrence of depression. Even during clinical remission, ruminative symptoms often persist and strongly predict relapse. Previous clinical observations and experimental studies suggest that aripiprazole, a partial dopamine D2 receptor agonist, can significantly improve cognitive symptoms and reduce rumination in MDD patients when added to selective serotonin reuptake inhibitors (SSRIs). However, rigorous randomized controlled trials (RCTs) directly targeting rumination and validating this effect remain limited. In this study, patients with acute MDD episodes and high levels of rumination will be randomly assigned to receive either escitalopram monotherapy (20 mg/day) or escitalopram (20 mg/day) plus low-dose aripiprazole (2.5-5 mg/day) for 8 weeks. Clinical assessments will be repeated during the 8-week treatment phase, including interim monitoring visits for efficacy and safety. The primary clinical endpoint is the change in Ruminative Responses Scale (RRS) scores from baseline to week 8.The assignment will remain blinded to outcome assessors and data analysts, while patients and treating clinicians will remain unblinded due to dose titration and safety monitoring requirements. Participants will undergo \[18F\]fallypride-PET-MRI scanning at baseline and and again at week 10, after tapering and discontinuation of aripiprazole during weeks 9-10, to measure striatal dopamine D2 receptor binding and explore its association with changes in rumination symptoms and treatment efficacy. The primary outcome is the change in Ruminative Responses Scale (RRS) scores. Secondary outcomes include changes in depressive symptoms and dopamine D2 receptor availability. This trial will provide neurobiological insights into the dopaminergic mechanisms underlying pathological rumination and explore the therapeutic potential of D2 receptor modulation in this cognitive domain.

Timeline

Start

2025-05-08

Primary completion

2026-04-08

Completion

2026-07-16

Publications

• Background van der Velden AM, Scholl J, Elmholdt EM, Fjorback LO, Harmer CJ, Lazar SW, O'Toole MS, Smallwood J, Roepstorff A, Kuyken W. Mindfulness Training Changes Brain Dynamics During Depressive Rumination: A Randomized Controlled Trial. Biol Psychiatry. 2023 Feb 1;93(3):233-242. doi: 10.1016/j.biopsych.2022.06.038. Epub 2022 Jul 22.
• Background Song AK, Hay KR, Trujillo P, Aumann M, Stark AJ, Yan Y, Kang H, Donahue MJ, Zald DH, Claassen DO. Amphetamine-induced dopamine release and impulsivity in Parkinson's disease. Brain. 2022 Oct 21;145(10):3488-3499. doi: 10.1093/brain/awab487.
• Background Wang Y, Lu Z, Xun G. Effect of aripiprazole on promoting cognitive function and enhancing clinical efficacy in patients with first-episode depression on escitalopram: A randomized controlled trial. J Affect Disord. 2024 Jan 1;344:159-168. doi: 10.1016/j.jad.2023.10.038. Epub 2023 Oct 10.
• Background Ehring T. Thinking too much: rumination and psychopathology. World Psychiatry. 2021 Oct;20(3):441-442. doi: 10.1002/wps.20910. No abstract available.

Drugs

Indications