The burden of disease and the IQ of nations

•The effect of different types of diseases on international IQ differences is examined.•The burden of disease is proxied by DALY rates.•Results show how considered diseases are strong predictors of IQ differences.•The strongest detrimental effect was found for perinatal and maternal diseases.

The relationship between the conditions of health of the population and the average intelligence quotients (IQs) was examined in a sample of 138 countries. Health conditions were proxied by DALY rates for infectious and parasitic diseases, perinatal and maternal conditions, and nutritional deficiencies. Results show how the burden of considered diseases – and, particularly, of perinatal and maternal – is strongly and negatively related to national IQs even when income, education, and temperature or latitude are controlled for. The effect of education on national IQs is significant, but lesser than that of health. The burden of disease is a strong predictor of international differences in average cognitive abilities. Investment in health in poor countries, and particularly in maternal and neonatal health, would have long-term economic returns by reducing international inequalities.