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. 2009 Dec 10:339:b5282.
doi: 10.1136/bmj.b5282.

The association of early IQ and education with mortality: 65 year longitudinal study in Malmö, Sweden

A Lager  1 , S Bremberg, D Vågerö
Affiliations

The association of early IQ and education with mortality: 65 year longitudinal study in Malmö, Sweden

A Lager et al. BMJ. .

Abstract

Objectives: To establish whether differences in early IQ explain why people with longer education live longer, or whether differences in father's or own educational attainment explain why people with higher early IQ live longer.

Design: Population based longitudinal study. Mortality risks were estimated with Cox proportional hazards regressions.

Setting: Malmö, Sweden.

Participants: 1530 children who took IQ tests at age 10 and were followed up until age 75.

Results: Own educational attainment was negatively associated with all cause mortality in both sexes, even when early IQ and father's education were adjusted for (hazard ratio (HR) for each additional year in school 0.91 (95% CI 0.85 to 0.97) for men and HR 0.88 (95 % CI 0.78 to 0.98) for women). Higher early IQ was linked with a reduced mortality risk in men, even when own educational attainment and father's education were adjusted for (HR for one standard deviation increase in IQ 0.85 (95 % CI 0.75 to 0.96)). In contrast, there was no crude effect of early IQ for women, and women with above average IQ had an increased mortality risk when own educational attainment was adjusted for, but only after the age of 60 (HR 1.60 (95 % CI 1.06 to 2.42)). Adding measures of social career over and above educational attainment to the model (for example, occupational status at age 36 and number of children) only marginally affected the hazard ratio for women with above average IQ (<5%).

Conclusions: Mortality differences by own educational attainment were not explained by early IQ. Childhood IQ was independently linked, albeit differently, to male adult mortality and to female adult mortality even when father's education and own educational attainment was adjusted for, thus social background and own social career seem unlikely to be responsible for mortality differences by childhood IQ. The clear difference in the effect of IQ between men and women suggests that the link between IQ and mortality involves the social and physical environment rather than simply being a marker of a healthy body to begin with. Cognitive skills should, therefore, be addressed in our efforts to create childhood environments that promote health.

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Conflict of interest statement

Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: (1) No financial support for the submitted work from anyone other than their employer; (2) No financial relationships with commercial entities that might have an interest in the submitted work; (3) No spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; (4) No non-financial interests that may be relevant to the submitted work.

Figures

None
Survival from age 60 years by sex and cognitive ability, adjusted for own educational attainment
See this image and copyright information in PMC

Comment in

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