title: Childhood IQ and all-cause mortality before and after age 65: prospective observational study linking the Scottish Mental Survey 1932 and the Midspan studies.
abstract: OBJECTIVE
  The objective was to investigate how childhood IQ related to all-cause mortality before and after age 65.
  
  
  METHODS
  The Midspan prospective cohort studies, followed-up for mortality for 25 years, were linked to individuals' childhood IQ from the Scottish Mental Survey 1932.
  
  
  METHODS
  The Midspan studies collected data on risk factors for cardiorespiratory disease from a questionnaire and at a screening examination, and were conducted on adults in Scotland in the 1970s. An age 11 IQ from the Scottish Mental Survey 1932, a cognitive ability test conducted on 1921-born children attending schools in Scotland, was found for 938 Midspan participants. The relationship between childhood IQ and mortality risk, adjusting for adulthood socio-economic confounders, was analysed. The effect of adjustment for childhood IQ on the relationship between established risk factors (blood pressure, smoking, height and respiratory function) and mortality was also investigated.
  
  
  RESULTS
  For deaths occurring up to age 65, there was a 36% increased risk per standard deviation decrease (15 points) in childhood IQ which was reduced to 29% after adjusting for social class and deprivation category. There was no statistically significant relationship between childhood IQ and deaths occurring after the age of 65. Adjustment for childhood IQ attenuated the risk factor-mortality relationship in deaths occurring up to age 65, but had no effect in deaths occurring after age 65.
  
  
  CONCLUSIONS
  Childhood IQ was significantly related to deaths occurring up to age 65, but not to deaths occurring after age 65.
authors.affiliation: Public Health and Health Policy, Division of Community Based Sciences, University of Glasgow, UK. c.l.hart@udcf.gla.ac.uk
authors.forename: C L
authors.initials: CL
authors.lastname: Hart
authors.forename: M D
authors.initials: MD
authors.lastname: Taylor
authors.forename: G Davey
authors.initials: GD
authors.lastname: Smith
authors.forename: L J
authors.initials: LJ
authors.lastname: Whalley
authors.forename: J M
authors.initials: JM
authors.lastname: Starr
authors.forename: D J
authors.initials: DJ
authors.lastname: Hole
authors.forename: V
authors.initials: V
authors.lastname: Wilson
authors.forename: I J
authors.initials: IJ
authors.lastname: Deary
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000401:mortality; D002423:Cause of Death; D002648:Child; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D007360:Intelligence; D008136:Longevity; D008297:Male; D008875:Middle Aged; D009026:Mortality; D011446:Prospective Studies; D011610:Psychosocial Deprivation; D012140:Respiratory Tract Diseases / Q000401:mortality; D018570:Risk Assessment / Q000706:statistics & numerical data; D012606:Scotland; D012959:Socioeconomic Factors; D016019:Survival Analysis