title: Long-term effectiveness of lithium in bipolar disorder: a multicenter investigation of patients with typical and atypical features.
abstract: OBJECTIVE
  Poor response to long-term lithium treatment has been reported to be associated with atypical features of bipolar disorder. The purpose of this study was to investigate the influence of atypical symptoms on the effectiveness and stability of long-term lithium treatment in a prospective, multicenter cohort of bipolar patients in a naturalistic setting.
  
  
  METHODS
  Patients were initially selected according to International Classification of Diseases, 8th Revision, criteria for bipolar disorder and required long-term treatment. Their diagnoses were reconfirmed according to DSM-IV upon its publication. They were prospectively followed for an approximately 20-year period ending in 2004 in 5 centers participating in the International Group for the Study of Lithium-Treated Patients. Examinations included a comprehensive psychiatric evaluation, an assessment of typical and atypical features on an 8-item scale, and an evaluation of clinical course using the morbidity index. Unbalanced repeated-measures regression models with structured covariance matrices were used to assess the extent to which the morbidity index was influenced by atypical symptoms, duration of treatment, and pretreatment features.
  
  
  RESULTS
  A total of 242 patients were followed for a mean period of 10 years. In 142 patients, the number of typical features was greater than the number of atypical features, whereas in 100 patients the number of atypical features was greater than or equal to the number of typical features. The mean morbidity index remained stable over a period of 20 years in both groups of patients and was not significantly associated with the presence of atypical features, the duration of lithium treatment, the number or frequency of episodes, or latency from the onset of bipolar disorder to the start of lithium treatment.
  
  
  CONCLUSIONS
  Our study suggests that long-term response to lithium maintenance treatment is stable both in patients with typical and in patients with atypical features. The predominance of either typical or atypical features did not result in different responses to long-term lithium treatment in this sample of bipolar patients.
authors.affiliation: Institute for Social Medicine, Epidemiology and Health Economics, Charité University Medical Center, 10098 Berlin, Germany. anne.berghoefer@charite.de
authors.forename: Anne
authors.initials: A
authors.lastname: Berghöfer
authors.forename: Martin
authors.initials: M
authors.lastname: Alda
authors.forename: Mazda
authors.initials: M
authors.lastname: Adli
authors.forename: Christopher
authors.initials: C
authors.lastname: Baethge
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Tom
authors.initials: T
authors.lastname: Bschor
authors.forename: Tasha
authors.initials: T
authors.lastname: Glenn
authors.forename: Paul
authors.initials: P
authors.lastname: Grof
authors.forename: Bruno
authors.initials: B
authors.lastname: Müller-Oerlinghausen
authors.forename: Janusz
authors.initials: J
authors.lastname: Rybakowski
authors.forename: Alexandra
authors.initials: A
authors.lastname: Suwalska
authors.forename: Andrea
authors.initials: A
authors.lastname: Pfennig
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018692:Antimanic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000523:psychology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016651:Lithium Carbonate / Q000008:administration & dosage* / Q000009:adverse effects; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D055502:Secondary Prevention; D055815:Young Adult
chemical_list: D018692:Antimanic Agents; D016651:Lithium Carbonate