Mental ability across childhood in relation to risk factors for premature mortality in adult life: the 1970 British Cohort Study

Objective: To examine the relation of scores on tests of mental ability across childhood with established risk factors for premature mortality at the age of 30 years. Methods: A prospective cohort study based on members of the British Cohort Study born in Great Britain in 1970 who had complete data on IQ scores at five ( N = 8203) or 10 ( N = 8171) years of age and risk factors at age 30 years. Results: In sex- adjusted analyses, higher IQ score at age 10 years was associated with a reduced prevalence of current smoking ( ORper 1 SD advantage in IQ 0.84; 95% CI 0.80, 0.88), overweight ( 0.88; 0.84, 0.92), obesity ( 0.84; 0.79, 0.92), and hypertension ( 0.90; 0.83, 0.98), and an increased likelihood of having given up smoking by the age of 30 years ( 1.25; 1.18, 1.24). These gradients were attenuated after adjustment for markers of socioeconomic circumstances across the life course, particularly education. There was no apparent relationship between IQ and diabetes. Essentially the same pattern of association was evident when the predictive value of IQ scores at five years of age was examined. Conclusions: The mental ability - risk factor gradients reported in the present study may offer some insights into the apparent link between low pre- adult mental ability and premature mortality.