Over one weekend in May 2004, three researchers in the University of Gothenburg's department of child and adolescent psychiatry shredded tens of thousands of documents, destroying all data from a 15 year longitudinal study following 60 Swedish children with severe attention deficit disorders.

What became known as the Gillberg affair began in 1996, at a community summer party on the Swedish island of Resö. Among the guests were Leif Elinder, a paediatrician recently returned to Sweden after several years spent working abroad, and Christopher Gillberg, professor of child and adolescent psychiatry at Gothenburg University.

The men had known each other since childhood, when they had met on the island most summers. Professor Gillberg had since become a world expert in autism and attention deficit disorder and a leading proponent of deficits in attention, motor control, and perception (DAMP), a Nordic concept developed in the 1970s to describe a combination of hyperactivity, lack of attention, and clumsiness and later regarded as a subcategory of attention deficit hyperactivity disorder.

What was said at that party depends on whom you ask, but both men agree they spoke briefly about Professor Gillberg's work, that Dr Elinder wanted to meet to discuss the work further, and that he was rebuffed. Dr Elinder says Professor Gillberg wasn't interested; Professor Gillberg says he simply didn't have the time.