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The term schizophrenia was introduced by Swiss psychiatrist Eugen Bleuler in 1911 to describe what he considered to be a group of severe mental illnesses with related characteristics; it eventually replaced the earlier term dementia praecox, which the German psychiatrist Emil Kraepelin had first used in 1899 to distinguish the disease from what is now called bipolar disorder. Individuals with schizophrenia exhibit a wide variety of symptoms; thus, although different experts may agree that a particular individual suffers from the condition, they might disagree about which symptoms are essential in clinically defining schizophrenia.
The annual prevalence of schizophrenia—the number of cases, both old and new, on record in any single year—is between 2 and 4 per 1,000 persons. The lifetime risk of developing the illness is between 7 and 9 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 early adulthood. More severe levels of impairment and personality disorganization occur in schizophrenia than in almost any other mental disorder.
Clinical features
The principal clinical signs of schizophrenia may include delusions, hallucinations, a loosening or incoherence of a person’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 individuals with schizophrenia may be persecutory, grandiose, religious, sexual, or hypochondriacal in nature, or they may be concerned with other topics. Delusions of reference, in which the person attributes a special, irrational, and usually negative significance to other people, objects, or events, are common in the disease. Especially characteristic of schizophrenia are delusions in which the individual believes his thinking processes, body parts, or actions or impulses are controlled or dictated by some external force.
Hallucinations are false sensory perceptions that are experienced without an external stimulus but that nevertheless seem real to the person who is experiencing them. Auditory hallucinations, experienced as “voices” and characteristically heard commenting negatively about the affected individual in the third person, are prominent in schizophrenia. Hallucinations of touch, taste, smell, and bodily sensation may also occur. Disorders of thinking vary in nature but are quite common in schizophrenia. 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 individuals with schizophrenia have little or no insight into their own condition and realize neither that they are suffering from a mental illness nor that their 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 or she is) may be disturbed. A person with schizophrenia may be apathetic and may lack the drive and ability to pursue a course of action to its logical conclusion, may withdraw from society, become detached from others, or become preoccupied with bizarre or nonsensical fantasies. Such symptoms are more typical of chronic rather than of acute schizophrenia.
Prior to DSM-5, different types of schizophrenia were recognized as well as intermediate stages between the disease and other conditions. The five major types of schizophrenia recognized by DSM-IV included the disorganized type, the catatonic type, the paranoid type, the undifferentiated type, and the residual type. Disorganized schizophrenia was characterized by inappropriate emotional responses, delusions or hallucinations, uncontrolled or inappropriate laughter, and incoherent thought and speech. Catatonic schizophrenia was marked by striking motor behavior, such as remaining motionless in a rigid posture for hours or even days, and by stupor, mutism, or agitation. Paranoid schizophrenia was characterized by the presence of prominent delusions of a persecutory or grandiose nature; some patients were argumentative or violent. The undifferentiated type combined symptoms from the above three categories, and the residual type was marked by the absence of these distinct features. Moreover, the residual type, in which the major symptoms had abated, was a less severe diagnosis. Distinguishing between the different types clinically, however, was limited by poor validity and low reliability of existing diagnostic criteria. DSM-5 encouraged clinicians to assess patients based on symptom severity.
Course and prognosis
The course of schizophrenia is variable. Some individuals with schizophrenia continue to function fairly well and are able to live independently, some have recurrent episodes of the illness with some negative effect on their overall level of function, and some deteriorate into chronic schizophrenia with severe disability. The prognosis for individuals with schizophrenia has improved owing to the development of antipsychotic drugs and the expansion of community supportive measures.
About 5 to 10 percent of individuals with schizophrenia die by suicide. The prognosis for those with schizophrenia is poorer when the onset of the disease is gradual rather than sudden, when the affected individual is quite young at the onset, when the individual has suffered from the disease for a long time, when the individual 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 employment record, or social isolation exist in the individual’s history.
Etiology
An enormous amount of research has been performed to try to determine the causes of schizophrenia. Family, twin, and adoption studies provide strong evidence to support an important genetic contribution. Several studies in the early 21st century have found that children born to men older than age 50 are nearly three times more likely to have schizophrenia than those born to younger men. 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 individuals with schizophrenia, and it is possible that brain damage, perhaps occurring at birth, may be a cause in some cases. Other studies suggest that schizophrenia is caused by a virus or by abnormal activity of genes that govern the formation of nerve fibers in the brain. Various biochemical abnormalities also have been reported in persons with schizophrenia. There is evidence, for example, that the abnormal coordination of neurotransmitters such as dopamine, glutamate, and serotonin may be involved in the development of the disease.
Research also has been performed to determine whether the parental care used in the families of individuals with schizophrenia contributes to the development of 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.
Treatment
The most-successful treatment approaches combine the use of medications with supportive therapy. New “atypical” antipsychotic medications such as clozapine, risperidone, and olanzapine have proved effective in relieving or eliminating such symptoms as delusions, hallucinations, thought disorders, agitation, and violent behavior. These medications also have fewer side effects than the more-traditional antipsychotic medications. Long-term maintenance on such medications also reduces the rate of relapse. Psychotherapy, meanwhile, may help the affected individual to relieve feelings of helplessness and isolation, reinforce healthy or positive tendencies, distinguish psychotic perceptions from reality, and explore any underlying emotional conflicts that might be exacerbating the condition. Occupational therapy and regular visits from a social worker or psychiatric nurse may be beneficial. In addition, it is sometimes useful to counsel the live-in relatives of individuals with schizophrenia. Support groups for persons with schizophrenia and their families have become extremely important resources for dealing with the disorder.
Mood disorders
Mood disorders include characteristics of either depression or mania or both, often in a fluctuating pattern. In their severer forms, these disorders include the bipolar disorders and major depressive disorder.
Major mood disorders
In general, two major, or severe, mood disorders are recognized: bipolar disorder and major depression.
Bipolar disorder (previously known as manic-depressive disorder) is characterized by an elated or euphoric mood, quickened thought and accelerated, loud, or voluble speech, overoptimism and heightened enthusiasm and confidence, inflated self-esteem, heightened motor activity, irritability, excitement, and a decreased need for sleep. Depressive mood swings typically occur more often and last longer than manic ones, though there are persons who have episodes only of mania. Individuals with bipolar disorder frequently also show psychotic symptoms such as delusions, hallucinations, paranoia, or grossly bizarre behavior. These symptoms are generally experienced as discrete episodes of depression and then of mania that last for a few weeks or months, with intervening periods of complete normality. The sequence of depression and mania can vary widely from person to person and within a single individual, with either mood abnormality predominating in duration and intensity. Manic individuals may injure themselves, commit illegal acts, or suffer financial losses because of the poor judgment and risk-taking behavior they display when in the manic state.
There are two types of bipolar disorders. The first, commonly known as bipolar 1, has several variations but is characterized primarily by mania, with or without depression. Its most common form involves recurrent episodes of mania and depression, often separated by relatively asymptomatic periods. The second type of bipolar disorder, typically called bipolar 2 (bipolar II), is characterized primarily by depression accompanied—often right before or right after an episode of depression—by a condition known as hypomania, which is a milder form of mania that is less likely to interfere with routine activities.
The lifetime risk for developing bipolar disorder is about 1 percent and is about the same for men and women. The onset of the illness often occurs at about age 30, and the illness persists over a long period. The predisposition to develop bipolar disorder is partly genetically inherited. Antipsychotic medications are used for the treatment of acute or psychotic mania. Mood-stabilizing agents such as lithium and several antiepileptic medications have proved effective in both treating and preventing recurrent attacks of mania.
Major depressive disorder is characterized by depression without manic symptoms. Episodes of depression in this disorder may or may not be recurrent. In addition, the depression can take on a number of different characteristics in different people, such as catatonic features, which include unusual motor or vocal behavior, or melancholic features, which include profound lack of responsiveness to pleasure. People with major depression are considered to be at high risk of suicide.
Symptoms of major depressive disorder include a sad or hopeless mood, pessimistic thinking, a loss of enjoyment and interest in one’s usual activities and pastimes, reduced energy and vitality, increased fatigue, slowness of thought and action, change of appetite, and disturbed sleep. Depression must be distinguished from the grief and low spirits felt in reaction to the death of a loved one or some other unfortunate circumstance. The most dangerous consequence of severe depression is suicide. Depression is a much more common illness than mania, and there are indeed many sufferers from depression who have never experienced mania.
Major depressive disorder may occur as a single episode, or it may be recurrent. It may also exist with or without melancholia and with or without psychotic features. Melancholia implies the biological symptoms of depression: early-morning waking, daily variations of mood with depression most severe in the morning, loss of appetite and weight, constipation, and loss of interest in love and sex. Melancholia is a particular depressive syndrome that is relatively more responsive to somatic treatments such as antidepressant medications and electroconvulsive therapy (ECT).
It is estimated that women experience depression about twice as often as men. While the incidence of major depression in men increases with age, the peak for women is between ages 35 and 45. There is a serious risk of suicide with the illness; of those who have a severe depressive disorder, about one-sixth eventually kill themselves. Childhood traumas or deprivations, such as the loss of one’s parents while young, can increase a person’s vulnerability to depression later in life, and stressful life events, especially where some type of loss is involved, are, in general, potent precipitating causes. Both psychosocial and biochemical mechanisms can be causative factors in depression. The best-supported hypotheses, however, suggest that the basic cause is faulty regulation of the release of one or more neurotransmitters (e.g., serotonin, dopamine, and norepinephrine), with a deficiency of neurotransmitters resulting in depression and an excess causing mania. The treatment of major depressive episodes usually requires antidepressant medications. Electroconvulsive therapy may also be helpful, as may cognitive, behavioral, and interpersonal psychotherapies.
The characteristic symptoms and patterns of depression differ with age. Depression may appear at any age, but its most common period of onset is in young adulthood. Bipolar disorders also tend to appear first in young adulthood.
Other mood disorders
Less-severe forms of mental disorder include dysthymia, or persistent depressive disorder, a chronically depressed mood accompanied by one or more other symptoms of depression, and cyclothymic disorder (also known as cyclothymia), marked by chronic, yet not severe, mood swings.
Dysthymia may occur on its own but more commonly appears along with other neurotic symptoms such as anxiety, phobia, and hypochondriasis. It includes some, but not all, of the symptoms of depression. Where there are clear external grounds for a person’s unhappiness, a dysthymic disorder is considered to be present when the depressed mood is disproportionately severe or prolonged, when there is a preoccupation with the precipitating situation, when the depression continues even after removal of the provocation, and when it impairs the individual’s ability to cope with the specific stress. Although dysthymia tends to be a milder form of depression, it is nevertheless persistent and distressing to the person experiencing it, especially when it interferes with the person’s ability to conduct normal social or work activities. In cases of cyclothymic disorder, the prevailing mood swings are established in adolescence and continue throughout adult life.
At any time, depressive symptoms may be present in one-sixth of the population. Loss of self-esteem, feelings of helplessness and hopelessness, and loss of cherished possessions are commonly associated with minor depression. Psychotherapy is the treatment of choice for both dysthymic disorder and cyclothymic disorder, although antidepressant medications or mood-stabilizing agents are often beneficial. Symptoms must be present for at least two years in order for a diagnosis of dysthymic or cyclothymic disorder to be made.
Major depressive disorder and dysthymia are much more prevalent than the bipolar disorders and cyclothymic disorder. The former disorders, which feature depressive symptoms exclusively, are also diagnosed more frequently in women than in men, whereas the latter tend to be diagnosed to about the same extent in women and men. Lifetime prevalence of major depression appears to be well over 10 percent for women and 5 percent for men. The prevalence for dysthymia is about 6 percent among the general population in the United States, but it is at least twice as common in women as in men. Lifetime prevalence rates reported for the bipolar disorders and cyclothymic disorder are roughly 1 percent or less.
