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schizophrenia (skĭtˌsəfrēˈnēə), group of severe mental disorders characterized by reality distortions resulting in unusual thought patterns and behaviors. Because there is often little or no logical relationship between the thoughts and feelings of a person with schizophrenia, the disorder has often been called “split personality.” However, the condition should not be confused with multiple personality, a disorder in which the individual has two or more distinct personalities that dominate at different times.

In 1896, the German psychiatrist Emil Kraepelin grouped what were previously considered unrelated mental diseases under the term dementia praecox. It was not until 1908, however, that an influential essay by Swiss psychiatrist Eugen Bleuler corrected Kraepelin's theory that the disease was an organic brain deterioration and thus incurable. Bleuler introduced the term schizophrenia to replace dementia praecox, emphasizing the dissociative phenomena in the mind and avoiding the implications of early onset and progressive brain deterioration.

Schizophrenic disorders generally begin in the late teenage years or early adulthood and tend to occur in withdrawn, seclusive individuals. The lifetime prevalence worldwide has been estimated to be just under 1%, and the disorder affects 1.5 to 2 million people in the United States alone. Symptoms include disturbances of thought, both in form and content (see delusion), and disturbances of perception, most commonly appearing as visual or aural hallucinations.

There are five major types of schizophrenia listed by the American Psychiatric Association in its Diagnostic and Statistical Manual of Mental Disorders. The most severe are disorganized (hebephrenic) schizophrenia, characterized by hallucinations, delusions, inappropriate laughing and crying, incoherent speech, and infantile behavior; and catatonic schizophrenia, characterized by physical rigidity or hyperactivity. Paranoid schizophrenics can often function relatively normally, although they may be disturbed by persecutory delusions and hallucinations, and they tend to exhibit argumentative behavior. The presence of a combination of symptoms from other types is classified as undifferentiated schizophrenia. Residual schizophrenia is constituted by minor symptoms, which occur as an active episode diminishes.

The cause of schizophrenia is unknown. Genetic factors appear to be involved in producing susceptibility to the condition, with studies among identical twins showing a 30%–50% concordance rate, a figure that has been confirmed by the results of adoption studies. Biochemical research suggests that high levels of the neurotransmitter dopamine, or excessive numbers of receptors for dopamine, may be at the root of schizophrenia. Medical imaging studies have revealed various physical and physiological anomalies in some patients. Other research has focused on mistiming of neural responses to stimuli in the brain. Many researchers maintain that a combination of influences, including such environmental factors as viral illness or malnutrition in the patient's mother during pregnancy, may lead to schizophrenia,

Antipsychotic drugs (see psychopharmacology), sometimes in conjunction with psychotherapy, have greatly improved the treatment of schizophrenia. Hospitalization is sometimes needed initially to provide basic personal needs (safety, food, and hygiene) while acute symptoms are treated. Most patients return to the community with varying degrees of independence and with good prospects for long-term remission of symptoms.


See R. Miller and S. Mason, Diagnosis: Schizophrenia (2002); studies by I. I. Gottesman (1991) and H. Häfner and W. F. Gattaz, ed. (1991).

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A brain disorder that is characterized by bizarre mental experiences such as hallucinations and severe decrements in social, cognitive, and occupational functioning. Patients with schizophrenia demonstrate a series of biological differences when compared to other groups of psychiatric patients. However, no biological marker has yet been found to conclusively indicate the presence of schizophrenia. A diagnosis is made on the basis of a cluster of symptoms reported by the patient, and of signs identified by the clinician.

People with schizophrenia may report perceptual experiences in the absence of a perceptual stimulus. Most common are auditory hallucinations, often reported in the form of words spoken to the person with schizophrenia. The language is often derogatory, and it can be tremendously frightening. See Hallucination

People with schizophrenia often maintain beliefs that are not held by the overwhelming majority of the general population. To be considered delusions, the beliefs must be unshakable. In many cases, these beliefs may be bizarre and stem from odd experiences. In some instances, the delusions have an element of suspicion to them, such as the belief that others are planning to cause the person harm. The delusions may or may not be related to hallucinatory experiences.

Many schizophrenics suffer from social isolation, lack of motivation, lack of energy, slow or delayed speech, and diminished emotional expression, often referred to as blunted affect. They may manifest an odd outward appearance due to the severity of their disorganization. This presentation may include speech that does not follow logically or sensibly, at times to the point of being incoherent. Facial expression may be odd or inappropriate, such as laughing for no reason. In some cases, people with schizophrenia may move in a strange and awkward manner. The extreme aspect of this behavior, referred to as catatonia, has become very rare since pharmacological treatments have become available.

Perhaps the most devastating feature of schizophrenia is the cognitive impairment found in most people with the disorder. On average, such people perform in the lowest 2–10% of the general population on tests of attention, memory, abstraction, motor skills, and language abilities.

The onset of schizophrenia generally occurs in people in the late teens to early twenties. However, schizophrenia is possible throughout the life span. While the onset of symptoms is abrupt in some people, others experience a more insidious process, including extreme social withdrawal, reduced motivation, mood changes, and cognitive and functional decline. The course of schizophrenia is normally characterized by episodes of relative remission in which only subtle symptoms remain, and episodes of exacerbation of symptoms, which are often caused by failure to continue treatment.

It is likely that there are various forms of schizophrenia, perhaps with different causes. Although schizophrenia appears to be inherited in some cases, the influence of genes is far from complete. Many arguments have been put forth regarding environmental factors that could cause schizophrenia. Very few of these theories are consistently supported.

Magnetic resonance imaging (MRI) has revealed that people with schizophrenia often have changes in the structure of their brain such as enlargement of the cerebral ventricles (the fluid-filled spaces in the brain close to the midline). Various brain regions have been found to be smaller in patients with schizophrenia, including the frontal cortex, temporal lobes, and hippocampi. In addition, studies of patients with schizophrenia have found patterns of abnormal activation of the brain while performing tests of memory and problem solving. See Brain, Medical imaging

Either a pharmacological or behavioral approach may be used in treating schizophrenia. A variety of antipsychotic medications have been used, and research continues into how to minimize the side effects which are often associated with such drugs. There are several targets for behavioral treatments in schizophrenia. Structured training programs have attempted to teach patients how to function more effectively in social, occupational, and independent living domains. Family interventions have been designed to provide a supportive environment for patients, and have been demonstrated to reduce risk of relapse. Another behavioral treatment area is teaching patients how to cope with hallucinations and delusions. Most patients with schizophrenia do not spontaneously recognize their symptoms as unusual and their experiences as unreal. Cognitive-behavioral treatments have been employed to help patients realize the nature of their symptoms and to develop plans for coping with them. See Psychopharmacology, Psychotherapy

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


Collins Dictionary of Sociology, 3rd ed. © HarperCollins Publishers 2000
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the commonest mental illness, characterized by the variety of its manifestations and by its tendency to become chronic.

As early as the 17th century, T. Willis observed adolescents who lost their childhood talents and became “grumbling fools” as young adults. In 1857 the French psychiatrist B. A. Morel identified dementia praecox as a form of “hereditary degeneration.” In the 1860’s and 1870’s the German psychiatrists K. L. Kahlbaum and E. Hecker described hebephrenia and catatonia. In 1888 the French psychiatrist V. Magnan identified the chronic hallucinatory-delusional psychoses that end in apathy and feeblemindedness. In 1898, E. Kraepelin classified these forms under the single heading of dementia praecox. E. Bleuler considered the splitting, or breakdown, of the unity of the psyche to be the most important symptom of the disease, and in 1911 he proposed that it be called schizophrenia. Bleuler, however, regarded schizophrenia—as many subsequent researchers did—only as a group of related diseases.

Progress in the study of schizophrenia is associated with the names of such Russian psychiatrists as V. Kh. Kandinskii, S. S. Korsakov, and P. B. Gannushkin. The different manifestations and varying course of schizophrenia were responsible for the lack of uniformity in nosologic definitions of the disease. In France, only the malignant form (that is, process schizophrenia) is regarded as schizophrenia, whereas in Great Britain and in the Scandinavian countries most forms of schizophrenia are treated as constitutionally or psychogenically determined separate psychoses. Some investigators divide this disorder into primary (or genuine) and symptomatic schizophrenia.

The causes of schizophrenia and the mechanisms of its development are still unclear. Most investigators consider it an endogenous disease in which hereditary predisposition is a factor. The importance of heredity in this respect has been confirmed by research studies of twins affected with schizophrenia. The hereditary factor varies in different forms of the disease. When the disease follows a constant course, members of the patient’s family often show symptoms of a deep schizoid psychopathy. In cases of intermittent bouts of schizophrenia, this form of the disease often develops in the patient’s close relatives as well. However, schizophrenia is not classified as one of the hereditary diseases proper; compared to the latter, it is far more prevalent, affecting approximately 0.8 percent of the population.

Studies of higher nervous activity in schizophrenics show the presence of protective inhibition (in the form of hypnotic phases) and foci of sluggish excitation. Electroencephalography and quantitative analysis are used in order to determine the abnormalities in the brain’s electrical activity that are characteristic of schizophrenia. Biological and biochemical studies have shown that immunological and other changes take place and that such changes vary with the form of schizophrenia. Neurochemical data indicate that in schizophrenia the metabolism of biogenic amines and enzymes is impaired. According to some investigators, the histological changes that occur in schizophrenia involve injury to the cerebral cortex; according to others, injury to the subcortical region.

Schizophrenia is usually classified according to the predominant symptoms or the specific course of the disease. To a greater or lesser degree, all forms of schizophrenia are progressive. According to the course of the disease, two basic types are distinguished—unintermittent and intermittent schizophrenia.

Unintermittent schizophrenia. Unintermittent schizophrenia is marked from its very onset by steadily intensifying disturbances (as manifested in reduced mental functioning) combined with monotonous “productive” symptoms, such as hallucinations. This type is subdivided into process, progressive, and nonprogressive schizophrenia.

Process schizophrenia usually develops in teen-agers and young adults and is generally known as hebephrenia. It is characterized by steadily progressive inactivity, emotional hypesthesia, and regressive behavior, accompanied by diverse but rudimentary productive symptoms. When it occurs in childhood, this form of schizophrenia (known as pseudo-oligophrenia) results in mental retardation.

Progressive schizophrenia is manifested in the form of a paranoid syndrome, which includes paranoia and paraphrenia; it usually occurs after the age of 30. It is marked by systematized delusions (for example, hypochondria or delusions of persecution or grandeur), combined with manifestations of psychic automatism—what is known as the Clérambault-Kandinskii syndrome, named after V. Kh. Kandinskii and the French psychiatrist G. de Clérambault (1872–1934); this consists of the feeling of being forcibly controlled by an outside influence and estrangement from one’s own mental activity, ending with paraphrenia. In some cases the delusions and hallucinations coexist with proper behavior and the ability to continue working; this is known as monomania or partial insanity, as it was called by 19th-century psychiatrists. Sometimes the disease does not develop beyond the stage of systematized delusions (paranoid schizophrenia).

Nonprogressive schizophrenia (also called latent, mild, pseudoneurotic, or psychopathiclike schizophrenia) is marked by the predominance of obsessions, cenesthesiopathy (vague sensations of bodily distress), manifestations of hypochrondria and hysteria combined with pronounced autism (predominance of self-centeredness and active withdrawal from the outside world), persistent asthenia, and emotional impoverishment.

Intermittent schizophrenia. Intermittent schizophrenia is characterized by the polymorphous development of various productive symptoms, such as affective delusions and dreams; mental disturbances appear only after an attack. Intermittent schizophrenia is subdivided into intermittent-progressive and periodic schizophrenia. The productive symptoms of intermittent schizophrenia, which outnumber the negative symptoms, are keenly perceptible to the senses, affective, and labile, and they are accompanied by feelings of confusion and excitation.

The clinical picture of intermittent-progressive schizophrenia is dominated by acute delusional fantasies, the automatism of the Clérambault-Kandinskii syndrome, and catatonic excitement. The vividness, plasticity, and affectivity of such disorders are less pronounced than in the case of periodic schizophrenia. Negative effects become evident after the first attack is over, sometimes growing more intense after each successive attack. The disease takes an almost unintermittent course and represents an intermediate variety between intermittent and unintermittent schizophrenia. In other cases, the negative manifestations occurring after the first attack either remain unchanged, in spite of successive similar attacks, or grow more intense after the fourth or fifth attack or even later—that is, irregularly. It is not unusual for a single attack of schizophrenia to occur, followed by a change in personality (for example, in the form of persistent asthenia).

Periodic schizophrenia (also called recurrent or schizo-affective) is marked by excitation, confusion, affective-delusional and oneiric incidents, and minor personality changes.

Unlike progressive and process schizophrenia, the intermittent and nonprogressive forms of the disease may occur at any age. It has been established that specific forms of schizophrenia are sexrelated. Process schizophrenia and unintermittently progressive schizophrenia are found more frequently in men than in women (the ratio being 3:1), whereas intermittent schizophrenia is more common in women (the ratio here being reversed). The overall incidence of the disease, however, is approximately the same among men and women.

Treatment. Treatment depends on the form of and the stage reached by the disease; it includes insulin therapy (where hypoglycemia is induced by injecting insulin), electroconvulsive therapy, occupational therapy, and psychotropic agents. Prophylactic measures are primarily directed at preventing acute manifestations of the disease and achieving more extended remission; they consist of preventive treatment—that is, small “maintenance” doses of psychotropic agents and proper working and living habits.

The high level of organization of inpatient and especially outpatient care, treatment by psychotropic agents, and occupational rehabilitation are significantly reducing the rate of permanent disability caused by schizophrenia. As research continues in this area, the opportunities for work rehabilitation are growing steadily. It is only the severe forms of schizophrenia that justify placing patients on disability, exempting them from military service, or limiting their choice of occupation. It is precisely for this reason that schizophrenia requires the kind of diagnosis known as binomial, which identifies not only the disease but also its specific form and course.


Shizofreniia [Klinika, patogenez, lechenie]. Moscow, 1969.
Shizofreniia: Mul’tidistsiplinarnoe issledovanie. Moscow, 1972.
Psychiatrie der Gegenwart, 2nd ed., vol. 2, part 1. Berlin, 1972.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A group of mental disorders characterized by withdrawal from reality and by alterations in thinking, feeling, and concept formations. Also known as dementia praecox.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


any of a group of psychotic disorders characterized by progressive deterioration of the personality, withdrawal from reality, hallucinations, delusions, social apathy, emotional instability, etc.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005