title: Negative symptoms and affective disturbance in schizophrenia and related disorders.
abstract: OBJECTIVE
  To review the data and discuss clinical recommendations for treating negative symptoms of schizophrenia. Negative symptoms (e.g., poverty of thought, affective blunting) have been regarded as part of schizophrenia since Kraepelin's early descriptions, although they remain a subject of controversy. For example, it is unclear if negative symptoms are distinct from other psychiatric symptoms such as depression, or are in actuality depression within schizophrenia. Recent evidence suggests that negative symptoms are independent of depression.
  
  
  METHODS
  Factor analytic studies have suggested that a negative factor (loss of affect, volition, poverty of thinking) may be distinguished from other components and is separable from a depression factor. Experimental use of vignettes have also been useful in the assessment of negative symptoms. A second controversial area is whether or not the presence or absence of affect is the fundamental issue separating schizophrenia from other psychoses.
  
  
  RESULTS
  A continuum of psychosis has been hypothesized, with unipolar psychotic depression at one pole and schizophrenia with defect state at the other. Within this proposed continuum, negative symptoms are associated only with schizophrenia without affect and with defect state schizophrenia. As such, variation in affect could be a primary determinant of the type of psychosis.
  
  
  CONCLUSIONS
  It appears that negative symptoms are a distinct aspect of schizophrenia and may aid in our understanding of psychotic disorders.
authors.affiliation: Department of Psychiatry, Victoria Hospital, London, Ontario.
authors.forename: A K
authors.initials: AK
authors.lastname: Malla
mesh_terms: D000342:Affective Symptoms / Q000175:diagnosis* / Q000523:psychology; D003702:Delusions / Q000175:diagnosis / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology; D003937:Diagnosis, Differential; D004409:Dyskinesia, Drug-Induced / Q000175:diagnosis / Q000523:psychology; D006212:Hallucinations / Q000175:diagnosis / Q000523:psychology; D006801:Humans; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000175:diagnosis*; D012565:Schizophrenic Psychology