Those who performed the best on memory, verbal reasoning and reaction time tests, were less likely to have genes linked to high blood pressure, develop diseases like Alzheimer’s, diabetes or have poor overall health. They were also likely to be taller and have larger brains, the study found.

The only conditions that intelligence appeared to increase were schizophrenia, autism and bipolar disorder.

“The study supports an existing theory which says that those with better overall health are likely to have higher levels of intelligence,” said Dr Saskia Hagenaars, of Edinburgh University.

Dr Stuart Ritchie, also of Edinburgh added: “This study tests whether genes that are linked to mental abilities and educational attainment are also genes that are related to some disorders.

“We found that there are many overlaps: to take one example, genes related to being taller are also related to obtaining a college or university degree.