title: A closer look at treatment resistant depression: is it due to a bipolar diathesis?
abstract: BACKGROUND
  Treatment resistant depression is a common clinical problem. Studies have shown that a large number of patients with depression do not have a satisfactory clinical outcome in spite of adequate trials of antidepressant drugs. In this study, we investigated demographic and clinical characteristics, diagnostic subtypes, and illness outcome of patients with resistant depression and a history of escape of response to adequate trials of at least two antidepressants for a previous episode.
  
  
  METHODS
  Sixty-one patients who were seen consecutively at a mood disorders clinic with the diagnosis of "unipolar" treatment resistant depression, and followed up for at least one year, were interviewed using the Structured Clinical Interview for DSM-IV. Prospectively collected data including the occurrence of episodes of hypomania, and supplemental information from family members on illness course were also used for purposes of diagnostic re-evaluation.
  
  
  RESULTS
  At intake, 35% of the patients were diagnosed as having a bipolar disorder. At follow-up, there was a 59% prevalence of bipolar disorder. Of the patients with major depressive disorder, 52% were subsequently classified as having bipolar spectrum disorder. The most important finding was that 80% of patients were found to show evidence of bipolarity. Moreover, the most common change in medication was a switch to mood stabilizers. CGI ratings showed significant improvement in functioning from the time of initial consultation.
  
  
  CONCLUSIONS
  This was a naturalistic study, and the data were collected in a non-blind fashion.
  
  
  CONCLUSIONS
  The findings suggest that the majority of cases of unipolar treatment resistant depression, occurring in the context of loss of antidepressant response, have a bipolar diathesis.
authors.affiliation: Mood Disorders Program, Regional Mental Health Care London, 850 Highbury Avenue North, P.O. Box 5532, Station B, London, ON, Canada N6A 4H1. vsharma@uwo.ca
authors.forename: Verinder
authors.initials: V
authors.lastname: Sharma
authors.forename: Mustaq
authors.initials: M
authors.lastname: Khan
authors.forename: Angela
authors.initials: A
authors.lastname: Smith
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001714:Bipolar Disorder / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy* / Q000523:psychology; D003865:Major Depressive Disorder / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy* / Q000523:psychology; D003937:Diagnosis, Differential; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010552:Personality Assessment; D011446:Prospective Studies; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D017211:Treatment Failure
chemical_list: D000928:Antidepressive Agents