title: Longitudinal course of cognitive deficits in bipolar disorder: a meta-analytic study.
abstract: OBJECTIVE
  Persistent cognitive deficits in bipolar disorder represent a major impediment to functional adjustment, but their static or progressive nature remains to be ascertained. The aim of this study was to synthesize findings from longitudinal research in order to examine the trajectory of cognitive impairment in bipolar disorder.
  
  
  METHODS
  A literature search was conducted through online databases covering the period between January 1990 and February 2014. Two approaches were undertaken. First, the results of longitudinal studies including neuropsychological assessment of stable bipolar patients at baseline and after a follow-up period of at least one year were meta-analyzed so as to obtain overall test-retest effect sizes for neurocognitive domains. Second, meta-analysis was restricted to longitudinal studies of bipolar patients including a control group. Patients' and controls' overall test-retest effect sizes were compared.
  
  
  RESULTS
  Bipolar patients' performance on 14 cognitive measures remained stable after a mean follow-up period of 4.62 years. When meta-analysis was restricted to controlled studies, no patient-control differences were found regarding longitudinal cognitive outcomes.
  
  
  CONCLUSIONS
  Test-retest differences for medication variables and mood state could not be controlled. Sufficient data were not available to investigate a wider array of neuropsychological domains. Furthermore, most primary studies included relatively short test-restest intervals.
  
  
  CONCLUSIONS
  To date, the available evidence from longitudinal studies is not in accordance with the hypothesis of a progressive nature of cognitive deficits in BD. The implications of this finding for further research are discussed.
authors.affiliation: Bipolar Disorders Program, Institute of Neurosciences, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Samamé
authors.affiliation: Bipolar Disorders Program, Institute of Neurosciences, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina.
authors.forename: Diego J
authors.initials: DJ
authors.lastname: Martino
authors.affiliation: Bipolar Disorders Program, Institute of Neurosciences, Favaloro University, Buenos Aires, Argentina; Institute of Cognitive Neurology (INECO), Buenos Aires, Argentina. Electronic address: sstrejilevich@ffavaloro.org.
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Strejilevich
mesh_terms: D001714:Bipolar Disorder / Q000523:psychology*; D003071:Cognition; D003072:Cognition Disorders / Q000523:psychology*; D006801:Humans; D008137:Longitudinal Studies
keywords: Bipolar disorder; Cognitive impairment; Longitudinal; Meta-analysis