title: Intelligence and neuroticism in relation to depression and psychological distress: Evidence from two large population cohorts.
abstract: Neuroticism is a risk factor for selected mental and physical illnesses and is inversely associated with intelligence. Intelligence appears to interact with neuroticism and mitigate its detrimental effects on physical health and mortality. However, the inter-relationships of neuroticism and intelligence for major depressive disorder (MDD) and psychological distress has not been well examined.
  
  
  
  Associations and interactions between neuroticism and general intelligence (g) on MDD, self-reported depression, and psychological distress were examined in two population-based cohorts: Generation Scotland: Scottish Family Health Study (GS:SFHS, n=19,200) and UK Biobank (n=90,529). The Eysenck Personality Scale Short Form-Revised measured neuroticism and g was extracted from multiple cognitive ability tests in each cohort. Family structure was adjusted for in GS:SFHS.
  
  
  
  Neuroticism was strongly associated with increased risk for depression and higher psychological distress in both samples. Although intelligence conferred no consistent independent effects on depression, it did increase the risk for depression across samples once neuroticism was adjusted for. Results suggest that higher intelligence may ameliorate the association between neuroticism and self-reported depression although no significant interaction was found for clinical MDD. Intelligence was inversely associated with psychological distress across cohorts. A small interaction was found across samples such that lower psychological distress associates with higher intelligence and lower neuroticism, although effect sizes were small.
  
  
  
  From two large cohort studies, our findings suggest intelligence acts a protective factor in mitigating the effects of neuroticism on psychological distress. Intelligence does not confer protection against diagnosis of depression in those high in neuroticism.
authors.affiliation: Division of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, EH10 5HF, UK. Electronic address: s1467731@sms.ed.ac.uk.
authors.forename: L B
authors.initials: LB
authors.lastname: Navrady
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Department of Psychology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Ritchie
authors.affiliation: Section of Clinical Psychology, University of Edinburgh, Medical Quad, Teviot Place, Edinburgh, EH8 9AG, UK.
authors.forename: S W Y
authors.initials: SWY
authors.lastname: Chan
authors.affiliation: NHS Greater Glasgow and Clyde, 1055 Great Western Road, Glasgow, G12 0XH, UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Kerr
authors.affiliation: Division of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, EH10 5HF, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Adams
authors.affiliation: Division of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, EH10 5HF, UK.
authors.forename: E H
authors.initials: EH
authors.lastname: Hawkins
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Medical Genetics Section, Centre for Genetics and Experimental Medicine, Institute for Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK; Generation Scotland, Centre for Genetics and Experimental Medicine, Institute for Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK.
authors.forename: D
authors.initials: D
authors.lastname: Porteous
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Department of Psychology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Generation Scotland, Centre for Genetics and Experimental Medicine, Institute for Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK.
authors.forename: I J
authors.initials: IJ
authors.lastname: Deary
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
authors.forename: C R
authors.initials: CR
authors.lastname: Gale
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Department of Epidemiology and Public Health, University College London, 1-19 Torrington Place, London, WC1E 6BT, UK; Alzheimer Scotland Dementia Research Centre, Department of Psychology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK.
authors.forename: G D
authors.initials: GD
authors.lastname: Batty
authors.affiliation: Division of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, EH10 5HF, UK; Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7, George Square, Edinburgh, EH8 9JZ, UK; Generation Scotland, Centre for Genetics and Experimental Medicine, Institute for Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: McIntosh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003865:Major Depressive Disorder / Q000523:psychology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D000075384:Neuroticism / Q000502:physiology*; D010551:Personality; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D013315:Stress, Psychological / Q000523:psychology*; D055815:Young Adult
keywords: Depression; Generation Scotland; Intelligence; Neuroticism; Psychological distress; UK Biobank