ABSTRACT

The psychotic disorders are probably the most dramatic of the psychiatric conditions, with their prominent delusions, hallucinations, and disorganized speech and behavior. The clarity of the psychotic phenotype makes it an ideal disorder to study from a genetic perspective. Interest in these disorders, especially schizophrenia, has led to some of the most comprehensive theories explaining their development. This chapter examines the behavioral genetic support for the most commonly accepted theory: that schizophrenia is a neurodevelopmental disorder in which a fixed brain lesion in early life interacts with maturational events that occur much later (Weinberger, 1987). This hypothesis is based on the idea that a brain lesion can remain clinically silent until normal developmental processes bring the structures affected by the lesion “on line” (Marenco & Weinberger, 2000).