title: Cleaving depressive diseases from depressive disorders and non-clinical states.
abstract: OBJECTIVE
  We sought to determine whether putative depressive diseases could be differentiated categorically from clinical depressive disorders and non-clinical mood states.
  
  
  METHODS
  We interviewed volunteers who reported or denied any lifetime depressive mood state and analyzed data from the former group reporting on their 'most severe' depressive episode. We employed latent class analysis (LCA) to determine whether a two-class solution was supported and the contribution of individual variables to class allocations.
  
  
  RESULTS
  All variables were significant predictors of class allocation. LCA-assigned Class I participants reported more depressive symptoms, had more distressing episodes and more lasting consequences, were more likely to view their depression as 'like a disease', and as being both disproportionately more severe and persistent in relation to any antecedent stressor. Validation involved comparison of LCA assignment with DSM-IV diagnosis for their most severe depressive episode. Of those assigned to Class I, 89% had a DSM diagnosis of melancholic, psychotic or bipolar depression. Class II had all those failing to meet criteria for a depressive episode and the majority of those with a non-melancholic depressive condition.
  
  
  CONCLUSIONS
  Despite not including individual depressive symptoms, study variables strongly differentiated putative depressive diseases from a composite of clinical depressive conditions and subclinical depressive states.
authors.affiliation: School of Psychiatry, University of New South Wales, Sydney, NSW, Australia.|Black Dog Institute, Sydney, NSW, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Parker
authors.affiliation: School of Psychiatry, University of New South Wales, Sydney, NSW, Australia.|Black Dog Institute, Sydney, NSW, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Paterson
authors.affiliation: School of Psychiatry, University of New South Wales, Sydney, NSW, Australia.|Black Dog Institute, Sydney, NSW, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Hadzi-Pavlovic
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis*; D003866:Depressive Disorder / Q000175:diagnosis*; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D007406:Interview, Psychological / Q000379:methods; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000175:diagnosis; D012720:Severity of Illness Index
keywords: bipolar disorder; depression; diagnosis; mood disorder; psychiatry