Treating children and young people with ADHD with stimulants helps protect them from developing mood and conduct disorders, a study confirms.

Harvard Medical School researchers have quantified the benefit of stimulants in preventing mental health disorders by determining the number of youngsters needed to be treated to prevent one event.

They found only three patients with ADHD needed stimulant treatment to prevent one from repeating a school grade or developing a conduct, anxiety or oppositional-defiance disorder.

Further, four patients with ADHD needed to be treated to prevent one from developing major depression and five needed to be treated to prevent one from developing bipolar disorder.