title: Testing the psychopathology of psychosis: evidence for a general psychosis dimension.
abstract: BACKGROUND
  Psychiatric taxonomists have sometimes argued for a unitary psychosis syndrome and sometimes for a pentagonal model, including 5 diagnostic constructs of positive symptoms, negative symptoms, cognitive disorganization, mania, and depression. This continues to be debated in preparation for impending revisions of the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases. We aimed to identify general and specific dimensions underlying psychopathological features of psychosis.
  
  
  METHODS
  The samples comprised 309 patients admitted to psychiatric services in the acute phase of their first or second episode of psychosis and 507 patients with enduring psychosis recruited from community mental health teams. Patients' symptoms were assessed on the Positive and Negative Symptom Scale. Analyses compared unitary, pentagonal, and bifactor models of psychosis.
  
  
  RESULTS
  In both samples, a bifactor model including 1 general psychosis factor and, independently, 5 specific factors of positive symptoms, negative symptoms, disorganization, mania, and depression gave the best fit. Scores of general and specific symptom dimensions were differentially associated with phase of illness, diagnosis, social functioning, insight, and neurocognitive functioning.
  
  
  CONCLUSIONS
  The findings provide strong evidence for a general psychosis dimension in both early and enduring psychosis. Findings further allowed for independent formation of specific symptom dimensions. This may inform the current debate about revised classification systems of psychosis.
authors.affiliation: Section of Social Psychiatry, Health Service and Population Research Department, Institute of Psychiatry, King's College London, London, UK. ulrich.reininghaus@kcl.ac.uk
authors.forename: Ulrich
authors.initials: U
authors.lastname: Reininghaus
authors.forename: Stefan
authors.initials: S
authors.lastname: Priebe
authors.forename: Richard P
authors.initials: RP
authors.lastname: Bentall
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000523:psychology*; D003072:Cognition Disorders / Q000523:psychology*; D003863:Depression / Q000523:psychology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000145:classification / Q000523:psychology*; D012559:Schizophrenia / Q000145:classification; D012565:Schizophrenic Psychology; D055815:Young Adult