IQ links CVD and socio-economic status

Differences in heart disease between people of high and low socio-economic statuses can be explained by a person’s IQ, a recent report has found. The study, published in the European Heart Journal, analysed detailed data from more than 4000 former USA soldiers over 15 years to examine differences in cardiovascular disease (CVD) risk factors and life expectancy between people of high and low socio-economic status. The report used the relative index of inequality (RII) to examine the relation between four widely used markers of socio-economic position, IQ test scores, a range of CVD risk factors, and later mortality to quantify the relation. The analysis found people on low incomes and with less education had a two to seven-fold higher risk of dying from CVD than people of a higher socio-economic status. "This confirmed what we already knew," the study’s authors said. "However, when we took into account IQ, we found this explained approximately 50% of that difference." Age-adjusted analyses also showed that IQ explained 63% of total mortality across the four socio-economic predictors, 63% for CVD and 65% of ‘other’ mortalities. IQ was found to explain 40% of total mortalities associated with cardiovascular risk factors, 40% of CVD cases and 43% of ‘other mortalities’. The effects of IQ among adult participants were also most pronounced among middle-aged males compared to early adulthood, although the same pattern was still present. “IQ scores have been shown to be inversely correlated with important chronic diseases… and have additional explanatory power on top of the classic variables such as smoking, high blood pressure, high blood glucose and obesity,” the study’s authors said. "It has partially explained the differences in death from heart disease.”European Heart Journal 2009; published online before print...