Child and adolescent psychiatry. In child and adolescent psychiatry (CAP), doctors work with children, young people (up to the age of 18) and their families. They treat a range of mental health problems and conditions including autism spectrum disorders, depression, anxiety, substance misuse and eating disorders.The child and adolescent psychiatrist is a physician who specializes in the diagnosis and the treatment of disorders of thinking, feeling and/or behavior affecting children, adolescents, and their families. Child and adolescent psychiatry or pediatric psychiatry is a branch of psychiatry that focuses on the diagnosis, treatment, and prevention of mental disorders in children, adolescents, and their families.