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This chapter discusses disorders characterized by psychosis. The definition of this state has been difficult to attain with certainty. At its simplest, it reflects a continuous disconnection of thought processes from reality. At times, it has been defined largely by the presence of hallucinations or delusions. In DSM-5, psychosis is characterized by hallucinations, delusions, disorganized thinking, grossly disorganized motor behavior, or negative symptoms, which are defined in the following discussion. None of these captures the sometimes subtle but often bizarre ideas and behaviors of individuals with psychosis or the experience of communicating with them being in the presence of a person with psychosis. While psychosis is a core feature of schizophrenia, it can be fully expressed in a number of acute states such as drug intoxications. Some of these aspects are discussed in Chap. 19 on “Delirium and Other Acute Confusional States.”
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Schizophrenia is among the most serious of all unsolved diseases. This was the opinion expressed 60 years ago in Medical Research: A Mid-Century Survey, sponsored by the American Foundation. Because of a worldwide lifetime prevalence of approximately 0.85 percent and particularly because of its onset early in life, its chronicity, and the associated social, vocational, and personal disabilities, the same conclusion is justified today (Carpenter and Buchanan). Schizophrenia has been found in every ethnic and social group so far studied. On average, 35 new cases per 100,000 population appear annually (Jablensky). The Global Burden of Disease Study derived from multiple sources (Charlson et al) gives estimates in 2016 of 0.28 percent of the world’s population, which do not vary greatly cross populations or regions. Estimates of the prevalence of schizophrenia and related psychotic disorders in the United States have been 0.25 to 0.64 percent. Despite the low incidence, the resultant number of years of life with disability are enormous.
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The incidence of schizophrenia has remained more or less the same over the past several decades. Males and females are affected with equal frequency. For unknown reasons, the incidence is higher in social classes showing high mobility and disorganization. It has been suggested that this is a by-product of “downward drift”—a result of deteriorating function in those with the disease that forces them into the lowest socioeconomic stratum where one finds poverty, crowding, limited education, and associated disadvantages—and the same data have been used to support the idea that schizophrenia can be caused by such social factors.
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Schizophrenic patients occupy about half the beds in psychiatric hospitals—more hospital beds than are allocated to any other single disease—and they constitute 20 to 30 percent of all new admissions to psychiatric institutions (100,000 to 200,000 new cases per year in the United States). The age of admission generally is between 20 and 40 years, with a peak between 28 and 34 years. The economic burden created by this disease is enormous—the direct and indirect costs in ...