title: The validity and internal structure of the Bipolar Depression Rating Scale: data from a clinical trial of N-acetylcysteine as adjunctive therapy in bipolar disorder.
abstract: Berk M, Dodd S, Dean OM, Kohlmann K, Berk L, Malhi GS. The validity and internal structure of the Bipolar Depression Rating Scale: data from a clinical trial of N-acetylcysteine as adjunctive therapy in bipolar disorder.
  
  
  BACKGROUND
  The phenomenology of unipolar and bipolar disorders differ in a number of ways, such as the presence of mixed states and atypical features. Conventional depression rating instruments are designed to capture the characteristics of unipolar depression and have limitations in capturing the breadth of bipolar disorder.
  
  
  METHODS
  The Bipolar Depression Rating Scale (BDRS) was administered together with the Montgomery Asberg Rating Scale (MADRS) and Young Mania Rating Scale (YMRS) in a double-blind randomised placebo-controlled clinical trial of N-acetyl cysteine for bipolar disorder (N = 75).
  
  
  RESULTS
  A factor analysis showed a two-factor solution: depression and mixed symptom clusters. The BDRS has strong internal consistency (Cronbach's alpha = 0.917), the depression cluster showed robust correlation with the MADRS (r = 0.865) and the mixed subscale correlated with the YMRS (r = 0.750).
  
  
  CONCLUSIONS
  The BDRS has good internal validity and inter-rater reliability and is sensitive to change in the context of a clinical trial.
authors.affiliation: 1Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Berk
authors.affiliation: 1Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Australia.
authors.forename: Seetal
authors.initials: S
authors.lastname: Dodd
authors.affiliation: 1Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Australia.
authors.forename: Olivia M
authors.initials: OM
authors.lastname: Dean
authors.affiliation: 1Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Australia.
authors.forename: Kristy
authors.initials: K
authors.lastname: Kohlmann
authors.affiliation: 1Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Australia.
authors.forename: Lesley
authors.initials: L
authors.lastname: Berk
authors.affiliation: 5Academic Discipline of Psychological Medicine, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Gin S
authors.initials: GS
authors.lastname: Malhi