The symptoms of schizophrenia are significant enough to cause a decline in the social and/or occupational functioning of affected persons.7 Although the etiology of schizophrenia remains unclear, it is certain that the combination of an unfavorable hereditary predisposition and unfavorable life experiences is a factor.8 The development of schizophrenia is not the result of a single inherited predisposition; rather, multiple physical, mental, inherited, and acquired traits can lead to the disorder.8 The combination of persistent negative symptoms and episodic displays of the positive symptoms of schizophrenia can have a profound effect on an individual’s activities of daily living, social functionality, and quality of life.9 

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According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, the diagnosis of schizophrenia is based on the presence of two or more symptoms (eg, delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, and negative symptoms) for a significant portion of time during a 1-month period.10 Since the onset of the disturbance, there should have been a significant portion of time when major areas of functioning have been impaired. The signs of the disturbance should have lasted for at least 6 months, with the 6 months including at least 1 month of symptoms.11,12 Also, during the prodromal period (before the full development of symptoms) or the residual periods (when prominent symptoms are absent), the disturbance may be manifested only by negative symptoms or by two or more negative symptoms.11 

For a patient to receive a diagnosis of schizophrenia, other disorders must be ruled out, such as schizoaffective disorder and mood disorders with psychotic features.12 Symptoms of a major depressive episode, manic episode, or mixed episode should not have occurred with the active-phase symptoms, and the disturbance is not the result of the direct physiologic effect of a substance.13,14 

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When schizophrenia is diagnosed, the illness can be categorized as paranoid, disorganized, or catatonic—the three main subtypes.15 Paranoid schizophrenia is characterized by a preoccupation with one or more delusions or the presence of frequent auditory hallucinations. Disorganized schizophrenia is characterized by disorganized speech, disorganized behavior, and a flat or inappropriate affect.15,16 Catatonic schizophrenia is characterized by prominent motor symptoms and nonreactivity to the environment.17 Undifferentiated schizophrenia is considered to be a type of schizophrenia in which symptoms of the disease are present but the criteria for the paranoid, disorganized, or catatonic type are not met.17 


Schizophrenia has been known to have an age of onset in the early twenties in men and the late twenties to early thirties in women. The incidence is generally equal in the two genders. In most patients, the illness fluctuates between acute episodes and periods of remission. 

Schizophrenia evolves in four phases. In the prodromal phase, a gradual development of symptoms may go unnoticed until a major symptom (eg, isolation, deterioration of hygiene, loss of interest in work or school, dysphoria) occurs. The acute phase consists of a full-blown episode of psychotic behavior. Patients may be unable to care for themselves.16,17 In the stabilization phase, the acute symptoms decrease; this phase may last several months. Lastly, in the stable phase, the symptoms markedly decline and may resolve. However, a complete remission without symptoms is uncommon in individuals with schizophrenia. 

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The pharmacotherapy of schizophrenia generally consists of the use of antipsychotic medications. Chlorpromazine was the first antipsychotic medication. Synthesized in the 1950s, the drug served as the prototype for many other antipsychotic agents, and numerous antipsychotic medication options have become available since then.18 The development of chlorpromazine led to the creation of additional first-generation (typical) antipsychotics. Subsequently, clozapine, the first second-generation (atypical) antipsychotic, was discovered in the 1950s and introduced into the market in the 1970s; it is used in a subset of individuals with psychotic disorder who have not benefited from conventional antipsychotic medications.19,20 

Both typical and atypical antipsychotic medications have been shown to be helpful in the treatment of the positive symptoms (eg, hallucinations, delusions), negative symptoms (eg, social withdrawal, poverty of speech), and cognitive symptoms (eg, reduction in working memory and attention) of schizophrenia.19 Antipsychotics are considered by  many to be the drugs of choice in the management and treatment of schizophrenia, with efficacy demonstrated through dopamine (D2) receptor antagonism for the typical antipsychotics and the combination of D2 and serotonin (5-hydroxytryptamine [5-HT2]) receptor antagonism for the atypical antipsychotics.20 

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