Health and intelligence may be the result of the same genetic factors (Image: Don Hammond / Design Pics Inc. / Rex Features )

In addition to checking blood pressure and heart rate, doctors may want to test their patients’ IQs to get a good measure of overall health.

A new study of 3654 Vietnam War veterans finds that men with lower IQs are more likely to suffer from dozens of health problems – from hernias, to ear inflammation, to cataracts – compared with those showing greater intelligence.

This offers tantalising – yet preliminary – evidence that health and intelligence are the result of common genetic factors, and that low intelligence may be an indication of harmful genetic mutations.


“It poses the question to epidemiologists: why is it that intelligence is a predictor for things that seem so very far removed from the brain,” says Rosalind Arden, a psychologist at King’s College London, who led the study.

Lifestyle choices

One obvious counter-argument is that intelligent people make healthier choices. “You could say: ‘look, brighter people make better health decisions – they give up smoking when they find it’s bad for you, they take up exercise when they find out its good for you, and they eat a lot of salad’,” Arden says.

That’s probably true, she says, yet her team found that indicators of healthy living, such as a low body mass index and not smoking, do not correlate with overall health of veterans as well as several tests of intelligence.

The researchers analysed data from a 1985 to 1986 study of Vietnam veterans led by the US Centers for Disease Control and Prevention into links between chemicals such as Agent Orange and health problems. Participants received thorough physical exams and took several intelligence tests.

Harmful mutations?

Arden’s team is aiming to find more evidence that health and intelligence are driven by common genetic factors. They previously showed, in the same group of Vietnam veterans, that more intelligent men produce healthier sperm, and they are currently working on a direct genetic test of their theory.

“I find the work pretty fascinating,” says Mark Prokosch, a psychologist at Elon University in North Carolina. He agrees that finding a link between harmful genetic mutations, health and intelligence will make a better case for Arden’s theory.

“I don’t think they have quite driven the nail in the coffin that there is clear evidence of this mutation load found in all of us that contributes to a fitness factor,” he says.

Journal reference: Intelligence (DOI: 10.1016/j.intell.2009.03.008)