Mental health disorders that are most frequent in the teenage years include those associated with: anxiety and depression, eating disorders, serious antisocial behaviour, attention deficit and hyperactivity disorder (ADHD) and self-harm. Teenage years are also the age when rarer psychotic disorders can emerge: half of all lifetime cases of psychiatric disorders start by age 14 and three quarters start by age 24. Overall, around 13% of boys and 10% of girls were rated as having some kind of disorder the Office for National Statistics survey of child and adolescent mental health in 2004
See the Office for National Statistics