Schizophrenia is a mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions. Although the course of schizophrenia varies among individuals, schizophrenia is typically persistent and can be both severe and disabling.

Symptoms of schizophrenia include psychotic symptoms such as hallucinations, delusions, and thought disorder (unusual ways of thinking), as well as reduced expression of emotions, reduced motivation to accomplish goals, difficulty in social relationships, motor impairment, and cognitive impairment. Although symptoms typically start in late adolescence or early adulthood, schizophrenia is often viewed from a developmental perspective. Cognitive impairment and unusual behaviors sometimes appear in childhood, and persistent presence of multiple symptoms represent a later stage of the disorder. This pattern may reflect disruptions in brain development as well as environmental factors such as prenatal or early life stress. This perspective fuels the hope that early interventions will improve the course of schizophrenia which is often severely disabling when left untreated.