Childhood IQ in relation to risk factors for premature mortality in middle-aged persons: the Aberdeen Children of the 1950s study
- 1MRC Social & Public Health Sciences Unit, Glasgow, UK
- 2Department of Psychology, University of Edinburgh, Edinburgh, UK
- 3MRC Social & Public Health Sciences Unit, University of Glasgow, Glasgow, UK
- Correspondence to: Dr G D Batty MRC Social & Public Health Sciences Unit, University of Glasgow, 4 Lilybank Gardens, Glasgow G12 8RZ, UK;
- Accepted 22 June 2006
Objective: A series of studies have shown an association between high childhood IQ scores and reduced rates of total mortality in adulthood. Several mechanisms have been advanced to explain these relationships, including mediation via established risk factors. This study examines the association between childhood IQ and a range of established physiological and behavioural risk factors for premature mortality in adulthood.
Design, setting and participants: In 1962, 12 150 children took part in a school-based survey when their IQ scores were extracted from educational records. When re-surveyed forty years later (n = 7183; 63.7% response), they self-reported information on risk factors for premature mortality (smoking, heavy alcohol consumption, obesity, height, hypertension and diabetes).
Main results: In sex-adjusted analyses based on an analytical sample of 5340 (2687 women), higher childhood IQ scores were associated with a decreased prevalence of ever having smoked regularly in adulthood (ORper SD increase in IQ (95% CI): 0.77 (0.73 to 0.81)), heavy alcohol consumption (0.89 (0.84 to 0.94)), obesity (0.78 (0.72 to 0.83)) and overweight (0.86 (0.81 to 0.91)). Higher IQ scores were similarly related to a reduced prevalence of short stature and higher rates of smoking cessation in smokers; effects that were stronger in women (p value for interaction: ⩽0.04). Adjusting for indicators of early and, particularly, later-life socioeconomic circumstances led to heavy attenuation of these gradients with statistical significance at conventional levels lost in most analyses.
Conclusions: The IQ–risk factor gradients reported may offer some insights into the apparent link between high pre-adult IQ and reduced mortality rates.
Competing interests: None declared.
All components of the study revitalisation have been granted various ethical committee permissions, including those from the Multi-centre Research Ethics Committee for Scotland, the Local Research Ethics Committee for Grampian (the region in which Aberdeen falls), and the London School of Hygiene & Tropical Medicine Research Ethics Committee. Tracing of study members using the General Register Office, Scotland, was approved by the Privacy Advisory Committee.
Contributors: David Batty generated the idea for this manuscript, which was developed by Sally Macintyre and Ian Deary. David Batty analysed the data and wrote the first draft of the manuscript. All coauthors made substantial contributions to subsequent revisions of the manuscript.