Having coined the term “schizophrenia“ to replace dementia praecox, Bleuler12 stated that schizophrenia “is not a disease in the strict sense, but appears to be a group of diseases [ ...] Therefore we should speak of schizophrenias in the plural.” Importantly,

Bleuler introduced a fundamental distinction between basic (obligatory) and accessory (supplementary) symptoms of the disorder. While the accessory symptoms comprised the delusions and hallucinations that today are commonly classified as “positive” symptoms, the basic symptoms included thought and Inhibitors,research,lifescience,medical speech derailment (“loosening of associations”), volitional indeterminacy (“ambivalence”), affective incongruence, and withdrawal Inhibitors,research,lifescience,medical from reality (“autism”). It was the presence of the basic symptoms that, according to Bleuler, gave schizophrenia its distinctive diagnostic profile. He acknowledged that the clinical subgroups of paranoid schizophrenia, catatonia, hebephrenia, and simple schizophrenia were not “natural” nosological entities and argued that “schizophrenia must be a much ABT-869 in vitro broader concept than the overt psychosis of the same name.” Along with the “latent” schizophrenias, which presented attenuated forms of the basic symptoms, manifesting as aberrant personality traits, he also listed within the “broader concept” atypical depressive or manic states, Wernicke’s Inhibitors,research,lifescience,medical motility psychoses, reactive psychoses,

and other nonorganic, nonaffective psychotic disorders as belonging to the group of schizophrenias, on grounds that “this is important for the studies of heredity,” thus foreshadowing the notion of schizophrenia spectrum disorders. Post-Kraepelinian and post-Bleulerian subtypes and dichotomies During the ensuing decades, a number of European and American clinicians Inhibitors,research,lifescience,medical proposed further subnosological distinctions within the widening phenotype of schizophrenia, including schizoaffective disorder,13 schizophreniform psychoses,14 process-nonprocess,15 and paranoid-nonparanoid schizophrenia.16 Schneider17 claimed that nine groups of psychotic manifestations,

designated as “firstrank symptoms” (FRS), Inhibitors,research,lifescience,medical had a “decisive weight” in the diagnosis of schizophrenia: audible thoughts; voices arguing about, or discussing, the patient; voices commenting on the patient’s actions; experiences of influences on the body; thought withdrawal no and other interference with thought; thought broadcast (diffusion of thought); delusional perception; and other experiences involving “made” impulses and feelings experienced as caused by an outside agency. Due to the sharpness of their definition and the hope that they could be reliably ascertained, the FRS were subsequently incorporated in the Research Diagnostic Criteria, RDC,18 DSM-III,19 and ICD-10.20 The Catego algorithm,21 used in the WHO cross-national studies, defined a “nuclear” schizophrenia (S+) characterized by presence of at least 3 out of 6 FRS.