Investigations conducted elsewhere

The role of intelligence in the incidence of health problems has become more important in recent years. The results available so far suggest that persistent concentration problems of people in the lower social strata relate to lower IQ levels in these groups (see for example: Batty GD, Der G, Macintyre S, Deary IJ. Does IQ explain socioeconomic inequalities in health? Evidence from a population based cohort study in the west of Scotland. British medical Journal 2006; 332: 580-584).