February 10, 2010

expert reaction to research into the association between IQ and cardiovascular disease, as published in European Journal of Cardiovascular Prevention and Rehabilitation

Scientists have found that a low IQ may be a predictor of heart disease and death, to a significant level second only to smoking. Experts, however, pointed out the caveats in the authors’ intepretation of their results.

Prof David Spiegelhalter, Winton Professor of The Public Understanding of Risk, University of Cambridge, said:

“I am a bit sceptical about this. The simple association is strong and interesting, but of course IQ is associated with so many other things. As they acknowledge, the authors are likely to have ‘over-adjusted’; when many highly correlated factors are looked at together it can be misleading to interpret the coefficients individually.

“In the fully adjusted analysis (Table 1) IQ is still there but look what happens to education and social class when they have been fully adjusted – they reverse correlations [Hazard ratio: >1 is positive correlation,

Fotini Rozakeas, Cardiac Nurse for the British heart Foundation (BHF), said:

“This study shows that IQ may be a factor in determining vulnerability to heart and circulatory disease particularly in lower socioeconomic groups.

“However, heart disease is largely preventable and many of the risk factors the study considered, such as smoking, physical inactivity, and high blood pressure, are ones we can all do something about.

“By making lifestyle changes such as stopping smoking, doing regular physical activity and eating a healthy balanced diet we can significantly reduce our risk of heart disease.

“In order to make real progress on tackling health inequalities we need health promotion campaigns designed to reach everyone in the community and encourage people to make healthy choices in food.

“We also need to create an environment which helps people make healthier choices. A quick and simple way to achieve this would be to introduce a single food labelling scheme using traffic light colours, guideline daily amounts and the word high, medium and low, and give shoppers simple at a glance information about the food they’re buying.”

Dr Ioanna Tzoulaki, Lecturer in Epidemiology, School of Public Health, Imperial College London, said:

“This study confirms the strong association between low IQ and increased risk of cardiovascular disease and mortality. Well-established risk factors for cardiovascular disease include diabetes mellitus, high blood pressure, smoking, obesity, physical inactivity and poor dietary habits. Whether IQ ranks amongst the top predictors of cardiovascular disease is of minor importance especially since this is difficult to examine and prove. The authors did not examine how well IQ predicts cardiovascular disease after known risk factors have been accounted for.

“However, the public health perspective of this research is important. Public health campaigns should focus on early life factors that have been shown to influence IQ levels and tackle social inequalities. At the same time, the public health messages for known risk factors such as diet may need to be simplified.”