title: Cognitive function and lifetime features of depression and bipolar disorder in a large population sample: Cross-sectional study of 143,828 UK Biobank participants.
abstract: BACKGROUND
  This study investigated differences in cognitive performance between middle-aged adults with and without a lifetime history of mood disorder features, adjusting for a range of potential confounders.
  
  
  METHODS
  Cross-sectional analysis of baseline data from the UK Biobank cohort. Adults aged 40-69 (n=143,828) were assessed using measures of reasoning, reaction time and memory. Self-reported data on lifetime features of major depression and bipolar disorder were used to construct groups for comparison against controls. Regression models examined the association between mood disorder classification and cognitive performance, adjusting for sociodemographic, lifestyle and clinical confounders.
  
  
  RESULTS
  Inverse associations between lifetime history of bipolar or severe recurrent depression features and cognitive performance were attenuated or reversed after adjusting for confounders, including psychotropic medication use and current depressive symptoms. Participants with a lifetime history of single episode or moderate recurrent depression features outperformed controls to a small (but statistically significant) degree, independent of adjustment for confounders. There was a significant interaction between use of psychotropic medication and lifetime mood disorder features, with reduced cognitive performance observed in participants taking psychotropic medication.
  
  
  CONCLUSIONS
  In this general population sample of adults in middle age, lifetime features of recurrent depression or bipolar disorder were only associated with cognitive impairment within unadjusted analyses. These findings underscore the importance of adjusting for potential confounders when investigating mood disorder-related cognitive function.
authors.affiliation: Mental Health and Wellbeing, Institute of Health and Wellbeing, University of Glasgow, Ground Floor, Office Block, Queen Elizabeth University Hospital, Glasgow, G51 4TF UK. Electronic address: Breda.Cullen@glasgow.ac.uk.
authors.forename: B
authors.initials: B
authors.lastname: Cullen
authors.affiliation: General Practice and Primary Care, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: B I
authors.initials: BI
authors.lastname: Nicholl
authors.affiliation: Public Health, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: D F
authors.initials: DF
authors.lastname: Mackay
authors.affiliation: Mental Health and Wellbeing, Institute of Health and Wellbeing, University of Glasgow, Ground Floor, Office Block, Queen Elizabeth University Hospital, Glasgow, G51 4TF UK.
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.affiliation: Public Health, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK; Institute of Public Health and Social Sciences, Khyber Medical University, Peshawar, Pakistan.
authors.forename: Z
authors.initials: Z
authors.lastname: Ul-Haq
authors.affiliation: Division of Psychiatry, University of Edinburgh, Edinburgh, UK.
authors.forename: A
authors.initials: A
authors.lastname: McIntosh
authors.affiliation: Department of Psychiatry, University of Oxford, Oxford, UK.
authors.forename: J
authors.initials: J
authors.lastname: Gallacher
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK.
authors.forename: I J
authors.initials: IJ
authors.lastname: Deary
authors.affiliation: Public Health, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Pell
authors.affiliation: Mental Health and Wellbeing, Institute of Health and Wellbeing, University of Glasgow, Ground Floor, Office Block, Queen Elizabeth University Hospital, Glasgow, G51 4TF UK.
authors.forename: J J
authors.initials: JJ
authors.lastname: Evans
authors.affiliation: Mental Health and Wellbeing, Institute of Health and Wellbeing, University of Glasgow, Ground Floor, Office Block, Queen Elizabeth University Hospital, Glasgow, G51 4TF UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000453:epidemiology / Q000523:psychology*; D003071:Cognition; D003072:Cognition Disorders / Q000453:epidemiology / Q000523:psychology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000453:epidemiology / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000523:psychology; D015995:Prevalence
keywords: Cognition; Epidemiology; Mania and bipolar disorder; UK Biobank; Unipolar depression