title: Is depression severity the sole cause of psychotic symptoms during an episode of unipolar major depression? A study both between and within subjects.
abstract: BACKGROUND
  Despite the common clinical assumption that psychosis is an indicator of severity in depression, it is not known what determines the presence of psychotic features in major depression. Our aim was to answer the question: Is depression severity the sole cause of psychotic symptoms during an episode of unipolar major depression?
  
  
  METHODS
  In a sample of 585 patients from the UK, meeting criteria for both DSM-IV and ICD-10 major recurrent depression, we assessed measures of severity of depression and the presence of psychotic features, both within and between subjects.
  
  
  RESULTS
  Within patients, psychotic episodes tended to be more severe than non-psychotic episodes. However, between patients there was wide variation in severity in both those that did, and did not, experience psychotic episodes.
  
  
  CONCLUSIONS
  We used retrospective interview information together with case note data. Our cases may not be typical of usual case loads because they were selected to avoid family history of bipolar illness or schizophrenia.
  
  
  CONCLUSIONS
  Individuals with a predisposition to psychotic features tend to display such features during more severe episodes of depression. However, patients with no history of psychosis may experience non-psychotic depressive episodes of equal or greater severity, in terms of depressive symptomatology, compared to patients with psychotic depression. Thus, there is individual variation in susceptibility to psychosis during mood episodes and severity is not the sole determinant.
authors.affiliation: Department of Psychological Medicine, School of Medicine, Cardiff University, University Hospital of Wales, Cardiff, CF14 4XN, UK.
authors.forename: Liz
authors.initials: L
authors.lastname: Forty
authors.forename: Lisa
authors.initials: L
authors.lastname: Jones
authors.forename: Ian
authors.initials: I
authors.lastname: Jones
authors.forename: Carly
authors.initials: C
authors.lastname: Cooper
authors.forename: Elen
authors.initials: E
authors.lastname: Russell
authors.forename: Anne
authors.initials: A
authors.lastname: Farmer
authors.forename: Peter
authors.initials: P
authors.lastname: McGuffin
authors.forename: Nick
authors.initials: N
authors.lastname: Craddock
mesh_terms: D000293:Adolescent; D000328:Adult; D000341:Affective Disorders, Psychotic / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000523:psychology*; D002648:Child; D003863:Depression / Q000453:epidemiology* / Q000523:psychology; D003865:Major Depressive Disorder / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D007406:Interview, Psychological; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013406:Suicide, Attempted / Q000523:psychology; D013997:Time Factors; D006113:United Kingdom; D055815:Young Adult