title: Neurocognitive function in bipolar disorder: a comparison between bipolar I and II disorder and matched controls.
abstract: BACKGROUND
  Cognitive deficits have been documented in patients with bipolar disorder. Further, it has been suggested that the degree and type of cognitive impairment differ between bipolar I and bipolar II disorder, but data is conflicting and remains inconclusive. This study aimed to clarify the suggested differences in cognitive impairment between patients with bipolar I and II disorder in a relatively large, clinically stable sample while controlling for potential confounders.
  
  
  METHODS
  67 patients with bipolar I disorder, 43 with bipolar II disorder, and 86 randomly selected population-based healthy controls were compared. A number of neuropsychological tests were administered, assessing verbal and visual memory and executive functions. Patients were in a stable phase during testing.
  
  
  RESULTS
  Patients with bipolar type I and type II were cognitively impaired compared to healthy controls, but there were no statistically significant differences between the two subtypes. The strongest predictor of cognitive impairment within the patient group was current antipsychotic treatment.
  
  
  CONCLUSIONS
  The present study suggests that the type and degree of cognitive dysfunction is similar in bipolar I and II patients. Notably, treatment with antipsychotics - but not a history of psychosis - was associated with more severe cognitive impairment. Given that patients with bipolar I disorder are more likely to be on antipsychotic drugs, this might explain why some previous studies have found that patients with type I bipolar disorder are more cognitively impaired than those with type II.
authors.affiliation: Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden. erik.palsson@neuro.gu.se
authors.forename: Erik
authors.initials: E
authors.lastname: Pålsson
authors.forename: Clara
authors.initials: C
authors.lastname: Figueras
authors.forename: Anette G M
authors.initials: AG
authors.lastname: Johansson
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Ekman
authors.forename: Björn
authors.initials: B
authors.lastname: Hultman
authors.forename: Josefin
authors.initials: J
authors.lastname: Östlind
authors.forename: Mikael
authors.initials: M
authors.lastname: Landén
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001288:Attention; D001714:Bipolar Disorder / Q000150:complications / Q000188:drug therapy / Q000523:psychology*; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests
chemical_list: D014150:Antipsychotic Agents