* One in 10 children has a clinically diagnosed mental disorder. These include emotional and behavioural disorders, depression, phobias, ADHD and autism.
* Ten per cent of 5 to 10-year-old boys have a mental disorder, compared to 5 per cent of girls. Thirteen per cent of 11 to 16-year-old boys have a mental disorder, compared to 10 per cent of girls.
* One in five children with a mental disorder has more than one. Three-quarters of children with multiple disorders are boys. Hyperactivity and hyperkinetic disorders are more likely to affect boys, almost all of them white. Eighty-two per cent of children with autism are boys.
* Emotional disorders, such as anxiety, depression and phobias, are twice as likely to affect girls as boys.
* Children with mental disorders are much more likely than others to take time off school, either because of truancy or health problems.
* Mental disorders are more common among children in lone-parent families, step-families, with a parent with no qualifications, with unemployed parents, and in poor or working-class families.
Source: Department of Health survey on the mental health of young people in 2004.