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CHAPTER 15 ■ Schizophrenia Spectrum and Other Psychotic Disorders
BOX 15–1 DSM-5-TR Criteria for Schizophrenia A. Two (or more) of the following, each present for a signif- icant portion of time during a 1-month period (or less if successfully treated). At least one of these must be (1), (2), or (3): 1. Delusions 2. Hallucinations 3. Disorganized speech (e.g., frequent derailment or incoherence) 4. Grossly disorganized or catatonic behavior 5. Negative symptoms (i.e., diminished emotional expression or avolition) B. For a significant portion of the time since the onset of the disturbance, level of functioning in one or more major areas, such as work, interpersonal relations, or self-care, is markedly below the level achieved prior to the onset (or when the onset is in childhood or adolescence, there is failure to achieve expected level of interpersonal, aca- demic, or occupational functioning). C. Continuous signs of the disturbance persist for at least 6 months. This 6-month period must include at least 1 month of symptoms (or less if successfully treated) that meet Criterion A (i.e., active-phase symptoms) and may include periods of prodromal or residual symptoms. During these prodromal or residual periods, the signs of the disturbance may be manifested by only negative
symptoms or by two or more symptoms listed in Crite- rion A present in an attenuated form (e.g., odd beliefs, unusual perceptual experiences). D.Schizoaffective disorder and depressive or bipolar disor- der with psychotic features have been ruled out because either (1) no major depressive or manic episodes have occurred concurrently with the active-phase symptoms; or (2) if mood episodes have occurred during active- phase symptoms, they have been present for a minority of the total duration of the active and residual periods of the illness. E. The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medica- tion) or another medical condition. F. If there is a history of autism spectrum disorder or a communication disorder of childhood onset, the addi- tional diagnosis of schizophrenia is made only if promi- nent delusions or hallucinations, in addition to the other required symptoms of schizophrenia, are also present for at least 1 month (or less if successfully treated). Specify if: First episode, currently in acute, partial, or full remission; Multiple episodes, currently in acute, partial or full remission; Continuous; Unspecified; With catatonia Specify current severity.
Source: Reprinted with permission from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (Copyright 2022). American Psychiatric Association.
Predisposing Factors The cause of schizophrenia is still uncertain. Most likely, no single factor can be implicated in the eti- ology; rather, the disease probably results from a combination of influences, including biological, psy- chological, and environmental factors. Biological Factors Refer to Chapter 2, “Biological Implications,” for a more thorough review of the biological implications of psychiatric illness. Genetics The body of evidence for genetic vulnerability to schizophrenia is growing. Studies show that rela- tives of individuals with schizophrenia have a much higher probability of developing the disease than does the general population. Whereas the lifetime risk for developing schizophrenia is about 0.7%, studies have shown that first degree relatives of an identified patient have up to a 9% greater risk of
developing schizophrenia than relatives of controls (Os & Reininghaus, 2017). The most compelling evidence for a genetic com- ponent in schizophrenia comes from twin studies. In monozygotic (identical) twins there is a 50% con- cordance rate for schizophrenia, which is four to five times the concordance rate in dizygotic twins or other first degree relatives (Boland & Verduin, 2022). Identical twins reared apart have the same rate of development of the illness as do those reared together. Because in about one-half of the cases only one of a pair of identical twins develops schizophre- nia, genetic makeup cannot be solely responsible for causing this disease. Os and Reininghaus (2017) suggest that additive and interacting combinations of genes, environmental factors, and the moderation of gene expression through interaction with environ- mental factors are probably all influential. How schizophrenia is inherited is uncertain. Cur- rent research is focused on determining which gene or genes are important in the predisposition to schizo- phrenia and what other biomarkers may predict risk
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