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CHAPTER 15 ■ Schizophrenia Spectrum and Other Psychotic Disorders
Theoretical Integration Accumulating evidence supports the concept of mul- tiple causation in the development of schizophrenia. Evidence gathered from a systematic review of the literature on schizophrenia (Matheson et al., 2014) suggests that schizophrenia is a widespread neural dysfunction accompanied by various psychological effects that respond moderately well to psychosocial and biomedical therapy: Patients have relatively poor cognitive functioning, and subtle, but diverse, structural brain alterations, altered electrophysiological functioning and sleep patterns, minor physical anomalies, neurological soft signs, and sensory alterations. There are mark- ers of infection, inflammation or altered immuno- logical parameters; and there is increased mortality from a range of causes. Risk for schizophrenia is increased with cannabis use, pregnancy and birth complications, prenatal exposure to T. gondii , child- hood central nervous system viral infections, child- hood adversities, urbanicity, and immigration (first and second generation), particularly in certain eth- nic groups. Developmental motor delays and lower intelligence quotient in childhood and adolescence are apparent. (p. 3387) Despite the wealth of research and knowledge that we have about schizophrenia, much more investigation is needed before we will fully understand this illness.
that greater numbers of individuals from the lower socioeconomic classes (in urban neighborhoods) experience symptoms associated with schizophrenia than do those from higher socioeconomic groups (Os & Reininghaus, 2017). These studies consis- tently find that lack of material resources (including housing and access to health care) and fragmented social relationships increase the risk for schizophre- nia, whereas social cohesion and ethnic density (the concentration of a given ethnic group in a particular area) are protective. An alternative view is the downward drift hypothe- sis , which suggests that because of the characteristic symptoms of the disorder, individuals with schizo- phrenia have difficulty maintaining gainful employ- ment and “drift down” to a lower socioeconomic level (or fail to rise out of a lower socioeconomic group). Proponents of this view consider poor social conditions to be a consequence rather than a cause
of schizophrenia. Stressful Life Events
No scientific evidence indicates that stress causes schizophrenia. It is probable, however, that stress may contribute to the severity and course of the illness. It is known that extreme stress can pre- cipitate psychotic episodes, so it may also precip- itate symptoms in an individual who possesses a genetic vulnerability to schizophrenia. Stressful life events also may be associated with exacerba- tion of schizophrenic symptoms and increased rates of relapse. Cannabis and Genetic Vulnerability Studies of genetic vulnerability for schizophrenia have linked certain genes ( COMT and ATK1 ) to increased risk for psychosis and particularly for ado- lescents with this genetic vulnerability who use canna- binoids (Radhakrishnan et al., 2014). Longitudinal studies suggest an up to 40% greater risk of psychosis in individuals who have ever used cannabis. Both can- nabis and synthetic cannabinoids can induce many schizophrenia-like symptoms. In individuals with a pre-existing psychosis, cannabinoids can exacerbate symptoms. Individuals with schizophrenia who con- tinue to use cannabis experience shorter periods of remission and more frequent relapses (J. Miller, 2020). More importantly, the increased risk for psy- chotic disorders such as schizophrenia with canna- bis use suggests the influence of lifestyle factors in the expression of genes and supports the theory that multiple factors play a role in the causality of this illness.
Other Schizophrenia Spectrum and Psychotic Disorders
The DSM-5-TR (APA, 2022) identifies a spectrum of psychotic disorders that are organized to reflect a gra- dient of psychopathology from least to most severe. Degree of severity is determined by the level, num- ber, and duration of psychotic signs and symptoms. Several disorders may carry the additional spec- ifier of With Catatonic Features. Catatonia refers to a significant motor disturbance that may range from stupor (no motor activity) to excessive motor activity and agitation. The disorders in which cata- tonia may appear include brief psychotic disorder, schizophreniform disorder, schizophrenia, schi- zoaffective disorder, substance-induced psychotic disorder, neurodevelopmental disorder, major depressive disorder, and bipolar disorders I and II (APA, 2022). The DSM-5-TR initiates the spectrum of disor- ders with Schizotypal Personality Disorder. For pur- poses of this textbook, this disorder is presented in Chapter 22, “Personality Disorders.”
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