Early life predictors of childhood intelligence: evidence from the Aberdeen children of the 1950s study
- Debbie A Lawlor1,
- G David Batty2,3,
- Susan M B Morton4,
- Ian J Deary3,
- Sally Macintyre2,
- Georgina Ronalds5,
- David A Leon5
- 1Department of Social Medicine, University of Bristol, UK
- 2MRC Social and Public Health Sciences Unit, University of Glasgow, Glasgow, Scotland
- 3Department of Psychology, University of Edinburgh, Edinburgh, Scotland
- 4School of Population Health, University of Auckland, Auckland, New Zealand
- 5Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, UK
- Correspondence to: Dr D A Lawlor Department of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, UK;
- Accepted 14 February 2005
Objective: To identify the early life predictors of childhood intelligence.
Design: Cohort study of 10 424 children who were born in Aberdeen (Scotland) between 1950 and 1956.
Results: Social class of father around the time of birth, gravidity, maternal age, maternal physical condition, whether the child was born outside of marriage, prematurity, intrauterine growth, and childhood height were all independently associated with childhood intelligence at ages 7, 9, and 11. The effect of social class at birth was particularly pronounced, with a graded linear association across the distribution even with adjustment for all other covariates (p<0.001 for linear trend). Those from the lowest social class (V) had intelligence scores that were on average 0.9–1.0 of a standard deviation lower than those from the higher groups (I and II) at each of the three ages of intelligence testing. Collectively, the early life predictors that were examined explained 16% of the variation in intelligence at each age.
Conclusions: Father’s social class around the time of birth was an important predictor of childhood intelligence, even after adjustment for maternal characteristics and perinatal and childhood factors. Studies of the association of childhood intelligence with future adult disease need to ensure that the association is not fully explained by socioeconomic position.
Funding: the Aberdeen children of the 1950s study was funded as a component project (G0828205) of a Medical Research Council Co-operative Group Life-course and trans-generational influences on disease risk (G9819083). A project on cognition and adult health in the cohort has been funded by the Chief Scientists Office, Scottish Executive Health Department; this provides G Ronald’s salary. D A Lawlor is funded by a UK Department of Health Career Scientist Award. When work on this began, G D Batty was supported by a University of Copenhagen Senior Research Fellowship; he is now funded by a Wellcome Trust Advanced Training Fellowship. I J Deary is the recipient of a Royal Society-Wolfson Research Merit Award. The views expressed in this publication are those of the authors and not necessarily those of any funding body.
Conflicts of interests: none declared.