IQ in early adulthood and later cancer risk: cohort study of one million Swedish men.

Full Abstract

BACKGROUND:
While several studies have reported an inverse relation between IQ and total mortality rates, little is known about the association, if any, between IQ and disease-specific outcomes, particularly cancer.

METHODS:
A cohort of 959,540 Swedish men who underwent IQ testing at military conscription at around 19 years of age, and who were followed for incident cancer. Hazards ratios for the relation between IQ and 20 cancer outcomes were computed using Cox regression.

RESULTS:
During an average of 19.5 years of follow-up, there were 10 273 new cancer cases. IQ showed few associations with the cancer end points studied. There was a suggestion that IQ was positively associated with lung cancer, and inversely related to stomach, oesophageal and liver malignancies, although effects were modest. The only robust gradient was found for IQ in relation to skin cancer (HRper one standard deviation advantage in IQ; 95% confidence interval 1.18; 1.13, 1.24; P value for trend across categories:
<0.01), which was attenuated but retained statistical significance after adjustment for indices of socioeconomic position across the life course.

CONCLUSIONS:
In this large cohort of Swedish men followed into middle age, IQ was related to very few of the cancer outcomes under investigation. This indicates that the recent observation that low IQ is related to increased mortality rates may not be generated by an IQ-cancer gradient. Given that the present analyses are among the first to examine these associations, replication is required.

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Author information

Author/s: Batty, G D (GD); Wennerstad, K Modig (KM); Smith, G Davey (GD); Gunnell, D (D); Deary, I J (IJ); Tynelius, P (P); Rasmussen, F (F);

Affiliation: MRC Social and Public Health Sciences Unit, University of Glasgow, Glasgow, UK.

Journal and publication information

Publication Type: Journal Article

Journal: Annals of oncology : official journal of the European Society for Medical Oncology / ESMO (Ann Oncol), published in England. (Language: eng)

Reference: 2007-Jan; vol 18 (issue 1) : pp 21-8

Dates: Created 2007/01/15; Completed 2007/04/05;

PMID: 17220284, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

Comments and Corrections

CommentIn: Ann Oncol. 2007 Jan;18(1):4-5. (PMID: 17220283)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Intelligence Tests
Male
Neoplasms - epidemiology; mortality; psychology
Risk Assessment
Risk Factors
Social Class
Survival Rate
Sweden - epidemiology

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