1. George Washington School of Medicine and Health Sciences, Washington, DC, USA
2. Children’s National Medical Center, Washington, DC, USA
3. McGill University, Montreal, Quebec, Canada
4. Douglas Hospital Research Centre, Montreal, Quebec, Canada
5. Yale University School of Medicine, New Haven, CT, USA
6. Yale Clinic for Attention and Related Disorders, New Haven, CT, USA
7. Dalhousie University, Halifax, Nova Scotia, Canada
8. IWK Health Centre, Halifax, Nova Scotia, Canada
9. New York University Child Study Center, New York City, USA
10. University of Michigan, Ann Arbor, USA
11. University of Illinois, Chicago, USA
12. University of British Columbia, Vancouver, Canada