Schizophrenia (SCZ) (pronounced /ˌskɪtsɵˈfrɛniə/ or /ˌskɪtsɵˈfriːniə/), from the Greek roots skhizein (σχίζειν, "to split") and phrēn, phren- (φρήν, φρεν-; "mind") is a psychiatric diagnosis that describes a mental disorder characterized by abnormalities in the perception or expression of reality. Distortions in perception may affect all five senses, including sight, hearing, taste, smell and touch, but most commonly manifest as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking with significant social or occupational dysfunction. Onset of symptoms typically occurs in young adulthood, with approximately 0.4–0.6% of the population affected. Diagnosis is based on the patient's self-reported experiences and observed behavior. No laboratory test for schizophrenia currently exists.
Studies suggest that genetics, early environment, neurobiology, psychological and social processes are important contributory factors; some recreational and prescription drugs appear to cause or worsen symptoms. Current psychiatric research is focused on the role of neurobiology, but no single organic cause has been found. Due to the many possible combinations of symptoms, there is debate about whether the diagnosis represents a single disorder or a number of discrete syndromes. For this reason, Eugen Bleuler termed the disease the schizophrenias (plural) when he coined the name. Despite its etymology, schizophrenia is not the same as dissociative identity disorder, previously known as multiple personality disorder or split personality, with which it has been erroneously confused.
Increased dopamine activity in the mesolimbic pathway of the brain is consistently found in schizophrenic individuals. The mainstay of treatment is antipsychotic medication; this type of drug primarily works by suppressing dopamine activity. Dosages of antipsychotics are generally lower than in the early decades of their use. Psychotherapy, and vocational and social rehabilitation are also important. In more serious cases—where there is risk to self and others—involuntary hospitalization may be necessary, although hospital stays are less frequent and for shorter periods than they were in previous times.
The disorder is thought to mainly affect cognition, but it also usually contributes to chronic problems with behavior and emotion. People with schizophrenia are likely to have additional (comorbid) conditions, including major depression and anxiety disorders; the lifetime occurrence of substance abuse is around 40%. Social problems, such as long-term unemployment, poverty and homelessness, are common. Furthermore, the average life expectancy of people with the disorder is 10 to 12 years less than those without, due to increased physical health problems and a higher suicide rate.