A phone-based ADHD therapy matches the effect size of in-person psychotherapy in a 337-person trial

Two million adults in Germany are estimated to have ADHD. The number of first-time diagnoses in adults has tripled since 2015. And yet the treatment infrastructure has not kept pace. Cognitive behavioral therapy, recommended by clinical guidelines as a core intervention, is scarce for adult ADHD patients. Waiting lists are long. Specialists are few. Many diagnosed adults receive no psychosocial treatment at all.

Into this gap steps a digital therapy called attexis, developed by GAIA in Hamburg. A randomized controlled trial (RCT) of 337 adults published in Psychological Medicine now provides the clinical evidence that the approach works, with effect sizes comparable to face-to-face psychotherapy for ADHD.

The trial design

Researchers from GAIA, Saarland University Medical Center, University Medical Center Mainz, University Hospital Bonn, University of Lubeck, and Kiel University enrolled 337 adults aged 18 and above with confirmed ADHD diagnoses. All participants continued their existing treatment (medication, psychotherapy, or whatever they were already receiving). Half were randomly assigned to also use attexis for three months.

The intervention group showed statistically significant and clinically relevant improvements in ADHD symptom severity compared with the control group receiving treatment as usual alone. But the benefits extended beyond the core diagnosis. Users also showed meaningful improvements in work and social functioning, self-esteem, quality of life, and a reduction in depressive symptoms.

How it works

Attexis is a self-guided program based on cognitive behavioral therapy (CBT) and mindfulness techniques. It delivers psychoeducation and therapeutic strategies through a conversational format on a smartphone or tablet, supplemented by self-monitoring tools and reminder functions. There is no therapist on the other end. The program is fully automated.

This matters for scalability. A human therapist can see a limited number of patients. A digital therapy can serve anyone with a smartphone and a prescription. In Germany, attexis was added to the DiGA (Digital Health Applications) directory by the Federal Institute for Drugs and Medical Devices in August 2025, making it the first permanently listed digital ADHD therapy for adults. It can be prescribed by doctors and psychotherapists, with costs covered by all statutory health insurance providers.

Comparable to face-to-face therapy

The most notable finding from the trial is the effect size. Digital interventions are often assumed to be weaker substitutes for in-person therapy. In this case, attexis produced effect sizes similar to those reported in trials of face-to-face CBT for adult ADHD. This is particularly relevant because the comparison is not against a placebo or waiting list but against treatment as usual, which in many cases already includes some form of care.

The program was also well-received by users, addressing a common concern with digital health tools: that patients will not actually use them. Engagement data suggest that the conversational format and self-monitoring features keep adults with ADHD, a population for whom sustained attention and follow-through are defining challenges, meaningfully involved with the program.

Limitations worth noting

The trial lasted three months. Whether the benefits of attexis persist after users stop the program, or whether continuous use is needed to maintain improvements, is unknown. ADHD is a chronic condition, and three-month outcomes, while encouraging, do not address long-term trajectory.

The study was conducted in Germany, where healthcare infrastructure, digital literacy, and insurance coverage for digital health applications differ from many other countries. Generalizing these results to settings with different healthcare systems requires caution.

GAIA, the developer of attexis, was directly involved in the research. While the multi-site university collaboration provides some independence, the developer's participation in the trial design and publication means the results should be weighed with that relationship in mind. Independent replication would strengthen the evidence base.

The trial also did not compare attexis directly with face-to-face CBT in a head-to-head design. The similarity in effect sizes is drawn from cross-study comparison, which is suggestive but not definitive. A randomized comparison between digital and in-person therapy would provide more conclusive evidence.

For the millions of adults with ADHD who currently lack access to evidence-based psychotherapy, however, a validated digital option with insurance coverage represents a practical improvement in available care, even with these caveats.