Schizophrenia is a mental disorder characterized by abnormalities in the perception or expression of reality. It most commonly manifests as auditory hallucinations, paranoid or bizarre delusions, ordisorganized speech and thinking with significant social or occupational dysfunction. Onset of symptoms typically occurs in young adulthood,[1] with around 0.4-0.6%[2][3] 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. As a result of the many possible combinations of symptoms, there is debate about whether the diagnosis represents a single disorder or a number of discrete syndromes. Despite the etymology of the term from the Greek roots skhizein ( “to split”) and phren, phren- ( “mind”), schizophrenia does not imply a “split mind” and it is not the same as dissociative identity disorder (previously known as multiple personality disorder or split personality), a condition with which it is often confused in public perception.

Increased dopamine activity in the mesolimbic pathway of the brain is consistently found in schizophrenic individuals. The mainstay of treatment is antipsychoticmedication; 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;[7] 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 ( about 5% ).

According to the revised fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), to be diagnosed with schizophrenia, three diagnostic criteria must be met:

Characteristic symptoms :

1. Delusions
2. Hallucinations
3. Disorganized speech, which is a manifestation of formal thought disorder
4. Grossly disorganized behavior (e.g. dressing inappropriately, crying frequently) or catatonicbehavior

If the delusions are judged to be bizarre, or hallucinations consist of hearing one voice participating in a running commentary of the patient’s actions or of hearing two or more voices conversing with each other, only that symptom is required above. The speech disorganization criterion is only met if it is severe enough to substantially impair communication.

Social/occupational dysfunction: For a significant portion of the time since the onset of the disturbance, one or more major areas of functioning such as work, interpersonal relations, or self-care, are markedly below the level achieved prior to the onset. Duration: Continuous signs of the disturbance persist for at least six months. This six-month period must include at least one month of symptoms (or less, if symptoms remitted with treatment).

If signs of disturbance are present for more than a month but less than six months, the diagnosis of schizophreniform disorder is applied.[4] Psychotic symptoms lasting less than a month may be diagnosed as brief psychotic disorder, and various conditions may be classed as psychotic disorder not otherwise specified. Schizophrenia cannot be diagnosed if symptoms of mood disorder are substantially present (although schizoaffective disorder could be diagnosed), or if symptoms ofpervasive developmental disorder are present unless prominent delusions or hallucinations are also present, or if the symptoms are the direct physiological result of a general medical condition or a substance, such as abuse of a drug or medication.