Background: Access to evidence-based psychosocial interventions for adults with Attention-Deficit/Hyperactivity Disorder (ADHD) remains limited, despite strong patient demand for non-pharmacological options such as cognitive behavioral therapy (CBT). Digital interventions may offer a scalable, low-threshold solution to meet this need and complement existing care. Methods: This pragmatic randomized controlled trial evaluated the effectiveness of attexis, a fully self-guided digital intervention based on CBT and mindfulness principles, as an adjunct to treatment as usual (TAU). A total of 337 adults with confirmed ADHD were randomized to either attexis + TAU or TAU alone. The primary outcome was ADHD symptom severity (Adult ADHD Self-Report Scale total score) at 3 months post-randomization (T1). Secondary outcomes included functional impairment, depressive symptoms, self-esteem, and health-related quality of life. Follow-up was conducted at 6 months (T2). Results: Intent-to-treat analyses showed significantly lower ADHD symptom severity in the intervention group at T1 (baseline-adjusted mean difference = -5.0 points; d = 0.85, p < .001). Significant improvements were also observed across all secondary outcomes, and effects remained stable at T2. Responder analyses confirmed the clinical relevance of the findings. Subgroup analyses demonstrated consistent effects across sex, medication use, psychotherapy status, and treatment changes. No adverse events related to attexis were reported. Conclusions: attexis was effective in reducing ADHD symptoms and improving a broad range of functional and psychosocial outcomes. As a safe, low-threshold, fully self-guided intervention, it may serve as a valuable adjunct to routine care and help address existing gaps in access to psychosocial treatment for adults with ADHD.

LTB and GAJ are employees of GAIA, the developer, owner, and manufacturer of attexis. AP declares that she served on advisory boards, gave lectures, performed phase‐3 studies, and received travel grants within the last 3 years from MEDICE Arzneimittel, Puetter GmbH and Co KG, Takeda, Boehringer, and receives royalties from books published by Elsevier, Hogrefe, Schattauer, Kohlhammer, Karger, Oxford Press, Thieme, Springer, Schattauer. EF declares that she receives royalties from Beltz Verlag and Elsevier Book, personal fees for supervision, workshops, and presentations on CBT, personality disorders, posttraumatic stress disorder and depression, is co-chair of the Deutsche Fachverband fuer Verhaltenstherapie e.V. (unpaid) and received payments from GAIA for consulting activities for designing digital therapeutics for patients for BPD as well as for presentations on schema therapy.

NCT06221930

This study was funded by GAIA, the developer, owner, and manufacturer of attexis.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Ethics Committee of the Medical Chamber Hamburg gave ethical approval for this work (reference number 2023-101052-BO-ff).

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The data produced in the present study are not publicly available due to proprietary reasons.