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Staying in education and lowered CHD risk: causal link investigated

By Nicole MacKee
People who spend an additional 3.6 years in education have a one-third lower risk of coronary heart disease (CHD), say researchers who have used genetic data to investigate a causal link between education and CHD risk.

In a mendelian randomisation study published in the BMJ, researchers analysed 162 genetic variants that had been previously associated with educational duration in 533,733 men and women.

They found that a genetic predisposition towards spending 3.6 additional years in education – the equivalent to an undergraduate university degree – lowered a person’s risk of CHD by about one-third (odds ratio 0.67).

A genetic predisposition towards more years in education was also associated with less smoking, lower body mass index and a favourable blood-lipid profile, the researchers said, noting that these factors could be mechanisms for the link.

The researchers ruled out reverse causation by testing for genetic variants that best predicted CHD.

Professor Leonard Kritharides, Professor of Medicine at The University of Sydney and Head of Cardiology at Concord Hospital, said the findings provided food for thought. He said mendelian randomisation analyses had been key in shoring up epidemiological evidence of cardiovascular risk factors such as high low-density lipoprotein (LDL) cholesterol, but the application of this research method to socially determined outcomes was novel.

‘Social scientists are looking at [mendelian randomisation] very seriously because a lot of their research is not amenable to randomised controlled trials,’ he said. ‘Mendelian randomisation is a bit like a natural experiment because it also gives you the lifetime effect of a particular characteristic.’

Professor Kritharides said there were many confounders to the findings – from the role of intellectual ability, social circumstance and personal discipline to the quality of education, and the wealth and political stability of the country – but they would lend support to ongoing efforts to maximise schooling time.

‘It would be helpful if this sort of research led us down the path to understanding what components of education are working to reduce the risk of CHD,’ Professor Kritharides said.

It may be ongoing exposure to sport, he said, or a greater understanding about the importance of avoiding smoking and making healthy lifestyle choices.

‘We need to see if there are opportunities all through the educational continuum to get people on the right track about the things that matter for long-term health.’
BMJ 2017; 358: j3542.

Picture credit: © woyzzeck/