One in 20 children and young adults in Ontario are diagnosed with attention deficit hyperactivity disorder (ADHD), and a high percentage of them are prescribed antipsychotic drugs, even though their rate of psychosis is low, according to researchers of a new study released on Wednesday. The study, published in The Canadian Journal of Psychiatry, found 11.9 per cent of young ADHD patients between the ages of 1 and 24 were prescribed antipsychotic medication.