Monday, 20 July 2009

IQ and health

Further evidence that Gottfredson was right today comes from Razib at GNXP: differences in IQ explain a decent chunk of the heart disease related mortality between high and low socioeconomic status groups. In short, poor people are, on average, less intelligent than richer people, and that difference explains some of the differences in health status.
Authors of the study published in the European Heart Journal on 15 July...analysed data from a group of 4,289 former soldiers in the USA. They found that IQ explained more than 20% of the difference in mortality between people from socio-economically disadvantaged backgrounds compared to those from more advantaged backgrounds. Importantly, this was in addition to the classical, known risk factors for heart disease, such as smoking and obesity.
"The difference between the second and third analyses showed that IQ alone explained a further 23% of the differences in mortality between the higher and lower ends of the socio-economic spectrum, in addition to the other, known risk factors," said Dr Batty. “IQ wasn’t a magic bullet in this study, but this psychological variable had additional explanatory power on top of the classic variables such as smoking, high blood pressure, high blood glucose and obesity. It has partially explained the differences in death from heart disease and all causes."
...there could be three possible explanations for Dr Batty's findings: "(i) intelligence might lead to greater knowledge about how to pursue healthy behaviours; (ii) intelligence may "cause" socioeconomic position, i.e. more intelligence leads to more education, income, occupational prestige . . .; and (iii) intelligence may be a marker for something else, and it is that something else, early life exposures, for example, that leads to mortality."....

I've longstanding complaints about the quality of work done in the public health field. First, utility is more than just health, something they typically ignore. Second, they are far to quick to chalk everything up to differences in socioeconomic status, and then make ridiculous policy claims, without stopping to consider that there might be underlying variables causing both differences in health and differences in economic outcomes. I'd discussed this a bit during my guest stint at EconLog in 2006, here.

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