Lifestyle factors, such as weight, blood pressure and smoking, explain around 40% of the protective effect of education on heart disease risk in later life, finds a study published by The BMJ today.
The results suggest that intervening on these "modifiable" risk factors would lead to reductions in cases of heart disease as a result of lower educational achievement.
But the researchers point out that more than half of this protective effect still remains unexplained and requires further investigation.
We already know that lower levels of education are directly related to higher cardiovascular risk in later life. But educational opportunities aren't the same for everyone, so the key to improving heart health in later life may lie in tackling the risk factors that drive these poorer outcomes.
To test this theory, an international team of researchers set out to investigate the role of body mass index (BMI), systolic blood pressure and smoking in explaining the protective effect of education on cardiovascular risk.
They carried out observational and genetic analysis of data from over 200,000 adults in the UK Biobank - a large population based study of more than half a million British men and women, in addition to a two-sample Mendelian randomisation approach from predominantly European studies.
This technique uses genetic information to avoid some of the problems that afflict observational studies, making the results less prone to unmeasured (confounding) factors, and therefore more likely to be reliable in understanding cause and effect.
In both observational and Mendelian randomisation analyses, the researchers found consistent evidence that BMI, blood pressure and smoking mediated the effect of education, explaining up to 18%, 27% and 34% respectively.
When all three risk factors were combined, they explained around 40% of the relationship between education and cardiovascular disease. And similar results were found for risk of stroke, heart attack, and all other types of cardiovascular disease.
As such, the researchers suggest that intervening on these risk factors "would lead to reductions in cardiovascular disease attributable to lower levels of education." But they say it is important to note that over half of the overall effect of education remain unexplained.
They point to some study limitations, for example the main analysis did not consider factors such as exercise, diet, cholesterol and blood sugar levels, and as participants were mostly white Europeans, findings may not be applicable to other populations.
Nevertheless, they stress that results were consistent across the two approaches and in additional sensitivity analyses,suggesting that the findings are robust.
These findings have "notable implications for policymakers as they identify potential strategies for reducing education inequalities in health," write the authors.
Further research identifying other related factors and the interplay between them - and in more diverse populations - will be key to reducing inequalities in cardiovascular disease, they conclude.