Schizophrenia

Schizophrenia is a mental disorder characterized variously by hallucinations (typically, hearing voices), delusions, disorganized thinking or behavior, and flat or inappropriate affect. Symptoms develop gradually and typically begin during young adulthood and rarely resolve. There is no objective diagnostic test; diagnosis is based on observed behavior, a psychiatric history that includes the person's reported experiences, and reports of others familiar with the person. For a formal diagnosis, the described symptoms need to have been present for at least six months (according to the DSM-5) or one month (according to the ICD-11). Many people with schizophrenia have other mental disorders, especially mood, anxiety, and substance use disorders, as well as obsessive–compulsive disorder (OCD).

The lifetime prevalence of developing schizophrenia is about 0.3% to 0.7%. In 2017, there were an estimated 1.1 million new cases and in 2022 a total of 24 million cases globally. Males are more often affected and on average have an earlier onset than females. The causes of schizophrenia may include genetic and environmental factors. Genetic factors include a variety of common and rare genetic variants. Possible environmental factors include being raised in a city, childhood adversity, cannabis use during adolescence, infections, the age of a person's mother or father, and poor nutrition during pregnancy.