The term schizophrenia was introduced by the Swiss psychiatrist Eugen Bleuler in 1911 to describe what he considered to be a group of severe mental illnesses with related characteristics; "schizophrenia" eventually replaced the earlier term dementia praecox, which the German psychiatrist Emil Kraepelin had first used in 1899 to distinguish the disease from manic-depressive psychosis.

Schizophrenic patients have a wide variety of symptoms; thus, although different authorities may agree as to whether a particular patient suffers from the condition, they might disagree about which constellations of symptoms are essential in clinically defining schizophrenia.

In 12 very different countries, rates for schizophrenia have been found to be surprisingly similar, the annual prevalence, that is, the number of cases both old and new recorded in one year, being between two and four per 1,000 persons. The lifetime risk of developing the illness is between seven and nine per 1,000.

Schizophrenia is the single largest cause of admissions to mental hospitals, and it accounts for an even larger proportion of the permanent populations of such institutions.

It is a severe and frequently chronic illness that typically first manifests itself during the teen years or during early adult life.

More severe levels of impairment and personality disorganization are reached in schizophrenia than in almost any other mental disorder.

Clinical features

The principal clinical signs of schizophrenia are delusions, hallucinations, a loosening or incoherence of a persons's thought processes and train of associations, deficiencies in feeling appropriate or normal emotions, and a withdrawal from reality.

A delusion is a false or irrational belief that is firmly held despite obvious or objective evidence to the contrary.

The delusions of schizophrenics may be persecutory, grandiose, religious, sexual, or hypochondriacal in nature, or they may be concerned with other topics.

Delusions of reference, in which the patient attributes a special, irrational, and usually negative significance to people, objects, or events in relation to himself, are common in the disease.

Especially characteristic of schizophrenia are delusions in which the patient believes his thinking processes, parts of his body, or his actions or impulses are controlled or dictated by some external force. Schizophrenic delusions are frequently bizarre or absurd.

Hallucinations are false sensory perceptions that are experienced without an external stimulus but that nevertheless seem real to the subject.

Auditory hallucinations, experienced as "voices" and characteristically heard commenting negatively about the patient in the third person, are prominent in schizophrenia. Hallucinations of touch, taste, smell, and bodily sensation also occur.

Disorders of thinking vary in nature but are quite common in schizophrenia. The thought disorders may consist of a loosening of associations, so that the speaker jumps from one idea or topic to another unrelated one in an illogical, inappropriate, or disorganized way.

At its most serious, this incoherence of thought extends into pronunciation itself, and the speaker's words become garbled or unrecognizable.

Speech may also be overly concrete and inexpressive; it may be repetitive, or, though voluble, it may convey little or no real information.

Usually a schizophrenic patient has little or no insight into his own condition and realizes neither that he is suffering from mental illness nor that his thinking is disordered.

Among the so-called negative symptoms of schizophrenia are a blunting or flattening of the person's ability to experience (or at least to express) emotion, indicated by speaking in a monotone and by a peculiar lack of facial expressions.

The person's sense of self (i.e., of who he is) may be disturbed. He may be apathetic and may lack the drive and ability to pursue a course of action to its logical conclusion, or he may withdraw from the world, become detached from others, and become preoccupied with silly, bizarre, or nonsensical fantasies.

Such symptoms are more typical of chronic rather than of acute schizophrenics.

Different authorities have recognized many different types of schizophrenia, and there are intermediate stages between the disease and other conditions. Four major types of schizophrenia are still recognized by the DSM-III: the disorganized or hebephrenic type, the catatonic type, the paranoid type, and the simple or undifferentiated type.

Hebephrenic schizophrenia is characterized by grossly inappropriate, shallow, or silly emotional responses and by incoherent thought and speech. Catatonic schizophrenia is marked by striking motor behaviour, such as remaining motionless in a rigid posture for hours or days, and by stupor or mutism.

Paranoid schizophrenia is marked by the presence of prominent delusions of a persecutory and/or grandiose nature.

Undifferentiated schizophrenia is marked by an insidious or gradual reduction in the person's interest in and relations with the external world and by a pervasive impoverishment of his personality and emotional responses.

Course and prognosis

The course of schizophrenic illness is extremely variable.

It may be said that roughly one-third of schizophrenic patients make a complete recovery and have no further recurrence, one-third have recurrent episodes of the illness, and one-third deteriorate into chronic schizophrenia with severe disability.

The prognosis for schizophrenics has improved during the 20th century due to the use of antipsychotic drugs and community supportive measures.

About 10 percent of schizophrenic patients die by suicide. The prognosis of schizophrenia is poor when it has a gradual rather than a sudden onset, when the patient is quite young at onset, when there is a long duration of illness, when the patient exhibits blunted feelings or has displayed an abnormal personality previous to the onset of the disease, and when such social factors as never having been married, poor sexual adjustment, a poor work record, or social isolation exist in the patient's personal history.


An enormous amount of research has been carried out to try to determine the causes of schizophrenia. Family, twin, and adoption studies provide strong evidence to support an important genetic contribution, but the mode of inheritance is not known.

Stressful life events are known to trigger or quicken the onset of schizophrenia or to cause relapse. Some abnormal neurological signs have been found in schizophrenics, and it is possible that brain damage, perhaps occurring at birth, may be a cause in some cases.

Various biochemical abnormalities have been reported in schizophrenics, but the evidence for the causal relevance of these abnormalities is incomplete.

Much research has been carried out to determine whether the types of communication used in the families of schizophrenics or the parental care in such families help produce the disease. There has also been extensive interest in such factors as social class, place of residence, migration, and social isolation. Neither family dynamics nor social disadvantage have been proved to be causative agents.


The most successful treatment approaches combine the use of drugs, psychotherapy, and supportive therapy.

In acute schizophrenia, phenothiazine, chlorpromazine, or butyrophenone drugs such as haloperidol are of proven efficacy in relieving or eliminating such symptoms as delusions, hallucinations, thought disorders, agitation, and violent behaviour.

Long-term maintenance on such drugs also reduces the rate of relapse.

Psychotherapy serves to relieve the patient's feelings of helplessness and isolation, buttress his healthy or positive tendencies, and help him to distinguish between his psychotic perceptions and reality and to deal with any underlying emotional conflicts that might be exacerbating his condition.

Occupational therapy for those in day care and regular visits from a social worker or community psychiatric nurse for outpatients are beneficial.

It is sometimes useful to counsel the relatives of schizophrenic patients living at home in their way of dealing with the patient's symptoms.