Pam Maras, of Greenwich University, said that in a study of 2,000 children aged 8-13, parents had identified 611 as hyperactive. Teachers identified 591, mainly different children. Teachers and parents only agreed on 147.
Boys were two and a half times more likely than girls to be identified as hyperactive, were more likely to be permanently excluded and more likely to have lower attainment levels.
Dr Maras said that young people were more likely to blame schools and teachers for their problems - as did parents, but to a lesser extent.
Teachers never accepted any responsibility.
She preferred to view ADHD as a biologicalpsychosocial problem that could be supported by inter-agency working with the involvement of parents and children.