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Longitudinal cohort study of childhood IQ and survival up to age 76

BMJ 2001; 322 doi: http://dx.doi.org/10.1136/bmj.322.7290.819 (Published 07 April 2001) Cite this as: BMJ 2001;322:819
  1. Lawrence J Whalley, professor of mental healtha,
  2. Ian J Deary (I.Deary{at}ed.ac.uk), professor of differential psychologyb
  1. a Department of Mental Health, University of Aberdeen, Clinical Research Centre, Cornhill Hospital, Aberdeen AB24 2ZD
  2. b Department of Psychology, University of Edinburgh, Edinburgh EH8 9JZ
  1. Correspondence to: I J Deary
  • Accepted 16 January 2001

Abstract

Objectives: To test the association between childhood IQ and mortality over the normal human lifespan.

Design: Longitudinal cohort study.

Setting: Aberdeen.

Subjects: All 2792 children in Aberdeen born in 1921 and attending school on 1 June 1932 who sat a mental ability test as part of the Scottish mental survey 1932.

Main outcome measure: Survival at 1 January 1997.

Results: 79.9% (2230) of the sample was traced. Childhood mental ability was positively related to survival to age 76 years in women (P<0.0001) and men (P<0.0001). A 15 point disadvantage in mental ability at age 11 conferred a relative risk of 0.79 of being alive 65 years later (95% confidence interval 0.75 to 0.84); a 30 point disadvantage reduced this to 0.63 (0.56 to 0.71). However, men who died during active service in the second world war had a relatively high IQ. Overcrowding in the school catchment area was weakly related to death. Controlling for this factor did not alter the association between mental ability and mortality.

Conclusion: Childhood mental ability is a significant factor among the variables that predict age at death.

What is already known on this topic

What is already known on this topic People in deprived conditions tend to have more illness and die younger

The reasons for this inequality in health are not fully established

What this study adds

What this study adds IQ at age 11 years was significantly associated with survival up to 76 years in an Aberdeen cohort

The association was unaffected by adjustment for overcrowding

Men with high IQ were more likely to die in active service in the second world war

Footnotes

  • Funding The chief scientist's office of the Scottish Executive and Henry Smith's Charities supported this research.

  • Competing interests None declared.

  • Accepted 16 January 2001
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