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A brief chronological review

In the 1980s, the European Union (EU) offered a scholarship to visit sister institutions to establish common educational programs. A visit of Professor Joe Sergeant to Professor Eric Taylor at the Institute of Psychiatry, King’s College London led to the idea that a joint training program on Hyperkinetic Disorders/ADHD and associated disorders for clinical researchers in Europe was overdue. Later, Ciba-Geigy (now ‘Novartis’) offered to support an inaugural meeting organized jointly by Professor Hans-Christoph Steinhausen and Professor Joe Sergeant in Zürich in 1987. At a subsequent meeting in Rome, it was decided by all participants that the initiative needed a name, and went for ‘EUNETHYDIS’ (European Network on Hyperkinetic Disorders).

Over the next 10 years, annual meetings took place to share and present crucial ADHD-related research in European centers. These meetings were chaired by Professor Joe Sergeant and hosted by local members of the network (names given in brackets) at the following sites: Santorini (Dr. Alexandra Roussos), Jerusalem (Dr. Judy Auerbach and Dr. Ruth Shalev), Antalya (Dr. Nese Erol), Lisbon (Dr. Antonio Fonseca), Capri (Dr. Adolfo Sadile), Toledo (Dr. Ana Meranda), Paris, Oslo (Professor Terje Sagvolden), Brugge (Dr. Herbert Roeyers), Mannheim (Professor Martin Schmidt), and Cagliari (Professor Alessandro Zuddas). The meetings served also to layout plans for a common research program.

An important grant application by Professor Terje Sagvolden was awarded by the EU in this period. This grant, Biopsychology of Hyperkinesia (BIOPHYRIS), enabled research teams from clinics, experimental psychology, and the biological sciences to collaborate. The research program was described by Sagvolden and Sergeant (1998). Links between the different areas of expertise within the program have been summarized by Taylor et al. (1998). The participating psychophysiology groups came from Amsterdam, Mannheim and Zurich and were coordinated by Professor Sergeant. The grant provided three postdoc positions, which were hold by Dr. Katya Rubia (Amsterdam), Dr. Teo van Leeuwen (Zurich), and Dr. Ben van ‘t Klooster (Mannheim). Contributions from animal research came from groups in Oslo and Naples headed by Professor Sagvolden and Dr. Sadile, respectively.

Joint research findings in various areas, including neuropsychology (Rubia et al., 1998; Sonuga-Barke et al., 1998), animal research (Boix et al., 1998; Carey et al., 1998; Papa et al., 1998; Russell et al., 1998; Sagvolden et al., 1998) psychophysiology (Oades, 1998; Brandeis et al., 1998; van Leeuwen et al., 1998), and assessment (Garcia-Rosales et al., 2021; Vitoratou et al., 2019) were published. Furthermore, both a monograph (Sergeant 1995) and a journal supplement (Rothenberger et al., 2004) reflected the state of the art and ongoing research of the various groups contributing to the network.

This research program demonstrated that EUNETHYDIS can deliver effective collaborative research in which the importance of training young researchers was emphasized and developed. For example, a special section of the EUNETHYDIS annual meeting is solely devoted to presentations by early career researchers (“Junior EUNETHYDIS”), followed by feedback from more senior members. During these sessions, most valuable input came from Professor James Swanson on how to evaluate therapeutic interventions, and which ‘rules of thumb’ might be useful for clinical practice.

Through a plan initiated by Professors Phil Asherson and Steve Faraone, the International Molecular Genetic study of ADHD (IMAGE) enabled various EUNETHYDIS centers to participate in a study of combined subtype ADHD at the clinical, neuropsychological and genetic levels. The contribution of data from EUNETHYDIS centers was substantial as evidenced by a large number of publications and a most fruitful ongoing cooperation within the Psychiatric GWAS Consortium (PGC) (Neale et al., 2010). This laid the seeds for later research projects supported by the EU.

In the 1990s, the need to define the clinical benchmarks for treating ADHD became a primary concern for EUNETHYDIS. Clinical guidelines for the disorder were developed (Taylor et al., 1998), updated (Taylor et al., 2004), and expanded (Banaschewski et al., 2006). Special attention was given to the management of adverse effects (Graham et al., 2011; Cortese et al., 2013), and to the quality of life of ADHD patients (Coghill et al., 2009; Danckaerts et al., 2009). This research was conducted by a EUNETHYDIS workgroup, which became known as the European ADHD Guidelines Group (EAGG).

The EAGG persisted in its activities by addressing several critical issues concerning clinical interventions in ADHD, for example the effectiveness of non-pharmacological interventions for ADHD. A systematic review and meta-analyses of dietary and psychological treatments were reported (Sonuga-Barke et al., 2013) and was followed by updated reviews and meta-analyses for behavioural interventions (Daley et al., 2014, 2018) as well as dietary interventions (Stevenson et al., 2014), cognitive training (Westwood et al., 2024), neurofeedback (Cortese et al., 2015; Cortese et al., 2016, Westwood et al., 2025) and clinical management in general (Cortese et al., 2020; Coghill et al, 2023). Critical evaluation of the effectiveness of medication in ADHD has been a crucial task of the EAGG workgroup, and has been conducted using a network analysis, indicating a clear effectiveness of most medications for ADHD (Cortese et al., 2018).

During the more recent years of collaborative EUNETHYDIS research, the importance of associated conditions such as autism, oppositional defiant disorder (ODD), conduct disorder (CD), learning disabilities and developmental coordination disorder (DCD) has been recognized. This work continues to show both the communalities and specificities of ADHD and associated disorders (Geurts et al., 2004, 2008; Mulligan et al., 2008; Niemeyer et al., 2010; de Jong et al., 2009; Fliers et al., 2009; Rommelse et al., 2009, van Lieshout et al., 2017; 2018) as well as emotional dysregulation, ODD, CD and substance abuse (Schoenmacker et al., 2018). Developmental changes accompanying ADHD in adolescence and adulthood have been given attention by EUNETHYDIS groups (Franke et al., 2018; Hartman, Geurts, Buitelaar & Rommelse, 2016; Helfer et al., 2018; Kooij et al., 2018) not only as clinical phenomena but also in terms of cortical development (Hoogman et al., 2017).

Following its establishment in 1987, for quite a number of years EUNETHYDIS represented a growing network of European researchers and clinicians tied to each other by shared scientific interests and a spirit of friendly cooperation and free communication without a strict organizational status. Professor Joe Sergeant served as the chairman supported by an informal advisory board (Eric Taylor, Terje Sagvolden, and subsequently Edmund Sonuga-Barke, Tobias Banaschewski, Dave Coghill and Alessandro Zuddas). With its growing membership and the visibility both in the world of research and in public, it was felt in 2011 that the time had come to give EUNETYDIS a more formal status in terms of organizational structure and bylaws, and to develop a constitution for Eunethydis. Thus, the formal position of a future steering committee was created.

When Joe Sergeant stepped down in 2013 and Tobias Banaschewski was elected as new chairman; Jan Buitelaar (treasurer), David Coghill (director of EUNETHYDIS International Conferences), Samuele Cortese (early career representative), Chris Hollis, Martin Holtmann, Emily Simonoff (convenor of the guidelines group) and Edmund Sonuga-Barke became members of the first Steering Committee. In 2017/18 Sven Bölte, Jonna Kuntsi, Anouk Scheres and Saskia van der Oord followed Chris Hollis, Martin Holtmann and Edmund Sonuga-Barke and Ting Mei took the new position of a Eunethydis secretary. In 2024, Sven Bölte and Jonna Kuntsi followed Tobias Banaschewski as new chairs, supported by the new Steering Committee: Samuele Cortese, Friederike Blume (early career representative), Tycho Dekkers, Pieter Hoekstra (treasurer), Kate Langley, Diane Purper-Ouakil and secretary Ting Mei. Between 2013 and 2023, membership doubled from 66 to more than 130. A website was created, strategies to foster early career development were intensified, mentorship programs developed, EUNETHYDIS Special Interest Groups were established for those interested in a particular area of research related to ADHD to further promote research and innovation related to ADHD, and the EUNETHYDIS Lifetime Achievement Award was created.

Recurrent conference topics addressed epidemiology and phenomenology, etiological and pathophysiological mechanisms, and trajectories. Unravelling the influence of genetics and environmental factors, brain structure and function, neuropsychological features, the relationship between ADHD and co-occurring mental and somatic disorders, and innovative approaches to optimise diagnostics, treatment and functional outcomes became increasingly important topics. Over the years, the conceptualization of ADHD changed from a distinct and categorical entity with clear boundaries towards the recognition that ADHD is characterized by marked heterogeneity on clinical, etiological, and pathophysiological levels, which is best understood as the extreme end of a spectrum. With the recognition that clinical and etiological variability between individuals represents a major obstacle to predict trajectories and functional outcomes across the lifespan and develop more effective interventions, efforts towards precision medicine with the goal to allocate pharmacological or psychosocial treatments based on the individual’s clinical, environmental, cognitive, genetic, or biological characteristics became an increasingly important topic. With the late 2010s, cultural and societal perspectives such as the role of stigmatization and self-stigmatization and debates about the neurodiversity perspective and whether ADHD could be conceptualised just as a natural entity became more prominent topics in the EUNETHYDIS conferences.

We are confident that the European centers that form the backbone of EUNETHYDIS will continue in meeting the aims of training junior clinical researchers, joining forces in effective research and providing best evidence-based knowledge of the treatment of ADHD and its associated disorders.

References

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