Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdrawal, decreased emotional expression, and apathy. Symptoms typically come on gradually, begin in young adulthood, and in many cases never resolve. There is no objective diagnostic test; the diagnosis is used to describe observed behavior that may stem from numerous different causes. Besides observed behavior, doctors will also take a history that includes the person's reported experiences, and reports of others familiar with the person, when making a diagnosis. To diagnose someone with schizophrenia, doctors are supposed to confirm that symptoms and functional impairment are present for six months (DSM-5) or one month (ICD-11). Many people with schizophrenia have other mental disorders, especially substance use disorders, depressive disorders, anxiety disorders, and obsessive–compulsive disorder.About 0.3% to 0.7% of people are diagnosed with schizophrenia during their lifetime. In 2017, there were an estimated 1.1 million new cases and in 2019 a total of 20 million cases globally. Males are more often affected and on average have an earlier onset, although some large reviews have not found gender differences in the prevalence of the disorder. The likely causes of schizophrenia 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, cannabis use during adolescence, infections, the ages of a person's mother or father, and poor nutrition during pregnancy.About half of those diagnosed with schizophrenia will have a significant improvement over the long term with no further relapses, and a small proportion of these will recover completely. The other half will have a lifelong impairment. In some cases people may be repeatedly admitted to hospitals. Social problems such as long-term unemployment, poverty, homelessness, exploitation, and victimization are commonly correlated with schizophrenia. Compared to the general population, people with schizophrenia have a higher suicide rate (about 5% overall) and more physical health problems, leading to an average decrease in life expectancy by 20 years. In 2015, an estimated 17,000 deaths were linked to schizophrenia.The mainstay of treatment is antipsychotic medication, along with counseling, job training, and social rehabilitation. Up to a third of people do not respond to initial antipsychotics, in which case the antipsychotic clozapine may be used. In situations where doctors judge that there is a risk of harm to self or others, they may impose short involuntary hospitalization. Long-term hospitalization is used on a small number of people with severe schizophrenia. In some countries where supportive services are limited or unavailable, long-term hospital stays are more common.