This chapter reviews the literature relating to schizophrenia in children and adolescents up to the 1970s. The historical study of schizophrenia highlights the remarkable degree of fluidity that has characterized its definition and diagnostic criteria and the special problems in relation to the existence and features of the disorder in children. There is conclusive evidence that children and young people were admitted alongside adult patients to private and public asylums. This practice continued into the twentieth century, until separate facilities were provided for juveniles, predominantly after the Second World War. A few authors described children displaying symptoms resembling premorbid characteristic of the early stages of schizophrenia. Multiple factors and morbid processes have been implicated in the causation of dementia praecox, schizophrenia and childhood psychosis. Treatment approaches have been remarkably diverse, often associated with evanescent, idiosyncratic etiological hypotheses and, generally, lacking evaluative research and controlled studies.

Hermann Emminghaus was the first to introduce a developmental perspective into child psychiatry, with special focus on psychoses. This chapter describes the general criteria for the classification of psychotic disorders in children and adolescents. In childhood and adolescence, however, age and developmental stage play a very important role in the classification of schizophrenia. The chapter discusses the psychotic disorders in childhood and adolescence and their relation to schizophrenia. Bettes and Walker found a strong effect of age on the manifestation of positive and negative symptoms. Positive symptoms increased linearly with age, while negative symptoms occurred most frequently in early childhood and late adolescence. About 50% of children and adolescents with schizophrenia show an uncharacteristic symptomatology in their premorbid personality. The chapter explains the classification of schizophrenia and other psychotic disorders according to International Classification of Diseases (ICD)-10 and Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV.