IQ affects heart disease risk in lower socioeconomic groups
15 July 2009
Dr David Batty, a Wellcome Trust Research Fellow at the Medical Research Council Social and Public Health Sciences Unit in Glasgow, and colleagues found that people on low incomes, in jobs with low prestige and with limited education had a higher risk of dying from cardiovascular disease and other causes than people of a higher socioeconomic status.
Moreover, the study found that IQ accounted for 23 per cent of the difference between the death rates among people from poorer and more advantage socioeconomic backgrounds, once age and classic known risk factors for heart disease such as smoking and obesity were taken into account.
Previous studies have shown that people from poor socioeconomic backgrounds have worse health and tend to die earlier from conditions such as heart disease, cancer and accidents.
Environmental exposure and health-related behaviours, such as smoking, diet and physical activity, can explain some of this difference, but not all of it. "This raises the possibility that, as yet, unmeasured psychological factors need to be considered - and one of these is intelligence or cognitive function: a person's ability to reason and problem-solve. IQ is strongly related to socioeconomic status," said Dr Batty.
The new study looked at a group of 4289 former soldiers in the USA.
"IQ alone explained 23 per cent of the differences in mortality between the higher and lower ends of the socioeconomic spectrum, in addition to the other, known risk factors," said Dr Batty.
Researchers speculate that this might be because intelligence leads to better knowledge about how to pursue healthy behaviours, or owing to the link between intelligence and socioeconomic position (more intelligence leads to more education, income, and more prestigious jobs).
It also provides further evidence that efforts to tackle socioeconomic inequalities could have far-reaching benefits on health.
"Initiatives aimed at raising living standards and education of the most disadvantaged families with children could potentially make a difference to those children's health and wellbeing in later life," said Dr Batty.
Image: Artwork showing pictures of hearts with ECG traces. Credit: Neil Leslie, Wellcome Images
Reference
Batty GD et al. Does IQ explain socio-economic differentials in total and cardiovascular disease mortality? Comparison with the explanatory power of traditional cardiovascular disease risk factors in the Vietnam Experience Study. Eur Heart J 2009.