IQ 'among the strongest predictors of cardiovascular disease'
10 February 2010
Researchers from the Universities of Edinburgh and Glasgow found that lower intelligence scores were associated with higher rates of cardiovascular disease and total mortality. Only smoking was a more powerful risk factor than IQ when it came to mortality risk.
While lower intelligence scores - as reflected by low results on written, spoken or oral tests of IQ - have been associated with a raised risk of cardiovascular disease, no study has so far compared the relative strength of this association with other established risk factors such as obesity, smoking and high blood pressure.
The new study looked at data collected in 1987 from 1145 Scottish men and women aged around 55 and followed up for 20 years. Data were collected for height, weight, blood pressure, smoking habits, physical activity, education and occupation; cognitive ability (IQ) was assessed using a standard test of general intelligence.
The researchers' analysis showed that the risk factor with the biggest influence on cardiovascular disease was cigarette smoking, followed by low IQ. Similar results were apparent when the health outcome was total mortality.
The scientists say that there a number of ways by which lower IQ scores could raise the risk of cardiovascular disease, notably that higher intelligence is associated with healthy behaviour, such as not smoking or exercise. A further possibility is that IQ denotes a "record of environmental insults," such as illness or poor nutrition, accumulated throughout life.
The individual skills reflected in a person's IQ may be important in the management of personal cardiovascular risk, said Dr David Batty, the Wellcome Trust Research Fellow who led the study.
"From a public health perspective, there is the possibility that IQ can be increased, with some mixed results from trials of early learning and school readiness programmes," said Dr Batty.
"It may also be worthwhile for health promotion campaigns to be planned with consideration of individual cognition levels."
The West of Scotland Twenty-07 Study is funded by the Medical Research Council.
Image: Artwork of an isolated heart attached to tubes instead of blood vessels. Credit: Oliver Burston, Wellcome Images
Reference
Batty GD et al. Does IQ predict cardiovascular disease mortality as strongly as established risk factors? Comparison of effect estimates using the West of Scotland Twenty-07 cohort study. Eur J Cardiovasc Prev Rehabil 2010 [Epub ahead of print].