CLINICAL HANDBOOK OF SCHIZOPHRENIA

11. Course and Outcome 101DIAGNOSIS AND ILLNESS COURSEGiven the ubiquitousness and cross-cultural robustness of the schizophrenic core syndrome,the disorder is broadly accepted as both common and consistent with the conceptof a disease. The diagnosis of schizophrenia shows good reliability over long periods oftime (e.g., from first admission to 10 years later). Furthermore, the negative symptoms ofschizophrenia and characteristic cognitive impairment are even more stable.The International Classification of Diseases (ICD) distinguishes diagnostic subtypeswith different patterns of symptoms, onset, and course. The simple type—a rare diagnosisthat does not involve psychotic symptoms—and the hebephrenic type show an insidiousonset and a chronic, unfavorable course. The undifferentiated type contains a mixture ofsymptoms from the other types except for catatonia. The rare catatonic type usuallyshows an acute onset, a remitting course, and an outcome involving only a low degree ofdisability. The paranoid type, the most frequent subtype, is characterized by delusions,hallucinations, and, in many cases, also pronounced thought disorder. The early illnesscourse of the paranoid type varies considerably from acute to insidious onsets.Longitudinal studies have shown a considerable overlap in the symptoms of the mostcommon types (i.e., paranoid and undifferentiated, or hebephrenic, schizophrenia).Hence, these subtypes are suboptimal constructs. The most simple categorization of thesymptoms of schizophrenia, for which the terms negative versus positive, or psychotic,are used, goes back to Émil Kraepelin. Attempts to distinguish these two symptom dimensionsas discrete etiological disease entities (type I: psychotic, attributed to dopaminergicdysfunction, type II: negative, with cognitive impairment attributed to earlyneurodevelopmental disorder) are not sufficiently supported by empirical data.Efforts to identify core symptom dimensions of schizophrenia have been more successful.Factor analyses of schizophrenia have consistently yielded at least four symptomdimensions: positive symptoms (i.e., reality distortion), negative symptoms (e.g., psychomotorpoverty, anhedonia), disorganization (e.g., inappropriate affect, thought disorder,disturbed speech, bizarre behavior), and depression. These factors constitute the mainsymptom dimensions of schizophrenia over the course of illness.WHEN DOES SCHIZOPHRENIA START?The neurodevelopmental hypothesis has made the question of the onset of schizophreniaa topical issue. The risk factors, which comprise pre- and perinatal complications, viralencephalitis and bacterial meningoencephalitis in infancy, early developmental delays andpremorbid deficits in cognitive and social functioning, and morphological changes in thebrain that persist during the illness course, suggest that the disorder starts during embryoniclife or soon afterwards.Critical views of the “simple neurodevelopmental model” argue that these risk factorsare not specific to schizophrenia and account only for a small proportion of cases.Furthermore, schizophrenia also develops in old age. The occurrence of psychosis and thepreceding onset of and increase in nonpsychotic symptoms should be regarded as representinga new disorder characterized by different types of symptoms and associated impairments.Anomalies of brain development in utero and in childhood are better seen asrisk factors, and the concomitant dysfunctions, as precursors of the disorder. The actualcourse of schizophrenia begins with the onset and accumulation of prepsychotic prodromaland subsequent psychotic symptoms.