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Introduction

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  • Diagnosis of Schizophrenia Is Based on Standardized Clinical Criteria

    • The Symptoms of Schizophrenia Can Be Grouped into Positive, Negative, and Cognitive

    • Schizophrenia Is Characterized by Psychotic Episodes

  • Both Genetic and Nongenetic Risk Factors Contribute to Schizophrenia

  • Neuroanatomic Abnormalities May Be a Causative Factor in Schizophrenia

    • Loss of Gray Matter in the Cerebral Cortex Appears to Result from Loss of Synaptic Contacts Rather Than Loss of Cells

    • Abnormalities in Brain Development During Adolescence May Contribute to Schizophrenia

  • Antipsychotic Drugs Act on Dopaminergic Systems in the Brain

  • An Overall View

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The success of neurobiology in providing insights into perception, cognition, and more recently emotion has inspired increasingly sophisticated biological investigations into disorders of thought and mood. In this chapter and the next we examine the four most serious disorders of thinking and mood: schizophrenia, depression, mania, and the anxiety states. These disorders involve disturbances in thought, self-awareness, perception, affect, volition, and social interaction.

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In addition to being scientifically challenging, mental illness such as schizophrenia is of great social importance. Tragically this illness results in lifelong disability. The World Health Organization counts schizophrenia as one of the most significant contributors to disease burden (defined as healthy years of life lost to illness) worldwide. Fully 5% of people with schizophrenia commit suicide. Many more are homeless. The vast majority are unable to function successfully in school or in the workplace. Before the advent of psychopharmacologic therapies, schizophrenia and the mood disorders accounted for more than half of all hospital admissions in the United States. Even now schizophrenia accounts for approximately 30% of all hospitalizations.

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The pattern of symptoms of schizophrenia are remarkably similar in all countries and cultures. The average prevalence worldwide ranges between 0.5 and 1%; the male-female ratio is 1.4:1. Diagnosis is usually made during late adolescence or early adulthood with the emergence of full symptoms, but in retrospect the illness begins far earlier with prodromal symptoms.

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Diagnosis of Schizophrenia Is Based on Standardized Clinical Criteria

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In medicine the understanding of a disease, and therefore its diagnosis, is ultimately based on identification of (1) etiological factors (such as microbes, toxins, or genetic risks) and (2) pathogenesis (mechanisms by which etiologic agents produce disease). Unfortunately, the etiology and pathogenesis of most mental disorders have not been determined. As a result, psychiatric diagnoses still rely on the patient's description of symptoms, the examiner's observations, a detailed natural history (the course of the illness over time), and the response to treatment.

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This approach to psychiatric diagnosis began at the turn of the 20th century with the work of Emil Kraepelin in Germany. Influenced by Rudolf Virchow, the German pioneer of cellular pathology, and by Thomas Sydenham, the English clinician who focused attention on the natural history of medical diseases, Kraepelin studied mental disorders as specific disease processes. Even without knowledge about the etiology and pathogenesis, of diseases affecting ...

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