Schizophrenia is one of the most devastating psychiatric disorders to affect children and adolescents. Although extremely rare before the age of 10, the incidence of schizophrenia rises steadily through adolescence to reach its peak in early adult life. The clinical severity, impact on development and poor prognosis of child- and adolescent-onset schizophrenia reinforce the need for early detection, prompt diagnosis and effective treatment.

The current concept of schizophrenia in children and adolescents evolved from a different perspective held during much of the 20th century. Until the early 1970s, the term childhood schizophrenia was applied to children who would now be diagnosed with autism. Kolvin's landmark studies distinguished children with early-onset (autistic) symptoms beginning in the first 2 years of life from children with a relatively ‘late-onset’ psychosis with onset of symptoms after age 6 or 7, which closely resembled adult schizophrenia (Hollis, 2008). Importantly, in ICD-9 (1978) and DSM-III (1980) the separate category of childhood schizophrenia was removed, and the same diagnostic criteria for schizophrenia were applied across the age range. The validity of the diagnosis of schizophrenia in childhood and adolescence is supported by follow-up studies into adulthood that show a high level of diagnostic stability (Hollis, 2000).

This chapter focuses on children and young people who meet ICD- 10 (World Health Organization, 1992) or DSM-5 (American Psychiatric Association, 2013) diagnostic criteria for schizophrenia. I use the term ‘adolescent schizophrenia’ as short-hand to refer to child and adolescent cases with onset up to 17 years of age. I examine evidence for continuities and discontinuities between adolescent schizophrenia and adultonset schizophrenia in terms of aetiology, premorbid features, clinical presentation, course and outcome, and treatment response. My goal is to summarise what is currently known about adolescent schizophrenia and to indicate the extent and limitations of the evidence base for clinical diagnosis, management and treatment.

Epidemiology

Incidence and prevalence

Gillberg et al (1986) calculated age-specific prevalences for all psychoses (including schizophrenia, schizophreniform disorder, affective psychosis, atypical psychosis and drug psychoses) using Swedish case-register data on 13- to 18-year-olds with psychotic illnesses. In 41% of cases the diagnosis was schizophrenia. At 13 years of age, the prevalence for all psychoses in the general population was 0.9 per 10 000, showing a steady increase during adolescence, reaching a prevalence of 17.6 per 10 000 at age 18 years.