If you are an agreeable type you are less likely to develop cancer, but you are more prone to heart disease.

If you are an extrovert you are at lower risk of the onset of heart disease, but if you are someone who is open to new experiences, you have a higher risk of developing depression and or anxiety.

These are some of the intriguing and statistically significant associations between personality traits and serious illness uncovered by the 2019 HILDA Survey of over 17,000 Australians.

The survey measured participant's dominant personality trait and compared whether they had developed a serious illness four years later.

It found that being conscientious may be good for you as it is associated with less likelihood of the onset of both heart disease and depression/anxiety. And being emotionally stable is associated with less chance of developing depression/anxiety and high blood pressure.

Professor Nick Haslam at the Melbourne School of Psychological Sciences says the idea that our personality traits directly influence our health has been popular since the 1950s, but despite many studies, the evidence is scant and inconsistent.

"When evidence has been found, those associations tend to be quite weak and difficult to interpret," says Professor Haslam.

Indeed, Professor Haslam points out that HILDA's finding that agreeableness is associated with heart disease conflicts with previous research that links heart disease to hostile personalities, the complete opposite of agreeableness.

But, he says, the association between emotional stability and lower depression/anxiety agrees with a large body of research.

Instead of directly influencing our health, Professor Haslam says, it is likely that links between personality traits and illness reflect the effects personality has on health-damaging and health-promoting behaviours.

"Personality traits influence how much people engage in behaviour that puts them at risk of ill health, like smoking, or protects them from it, like exercise," says Professor Haslam.

"This is one reason why, as the HILDA study confirms, conscientious people who think of the future, make plans and stick to them, tend to have better health and to live longer."

Managed by the University of Melbourne, the HILDA (Household Incomes and Labour Dynamics in Australia) Survey, is filled out by the same group of Australian households every year, creating a unique picture of how Australians are faring and changing over time.

Every four years, it includes detailed health questions, giving researchers the opportunity to compare people's circumstances with the onset of serious illness.

And as with personality traits, some of the associations appear to be common sense, others are fascinating, and then there are the ones that are just, well, weird.

For example, having your spouse or child die is actually associated with reduced risk of the onset of heart disease, and isn't significantly associated with the onset of any serious illness.

However, people with a seriously injured or ill family member are at higher risk of developing heart disease.

The data reveals no association between poverty and the onset of serious illness, though financial stress is associated with a higher risk of developing cancer. Unemployment is also associated with the onset of heart disease, and having a job is associated with a lower risk of developing depression/anxiety.

At the other end of the scale, having a high income also means you are less likely to develop depression/anxiety, but it does make you more likely to develop high blood pressure.

Another interesting finding was that working long hours (that is, more than 50 hours a week) wasn't associated with any greater or lesser onset risk of serious illness.

When it comes to family and household types, couples with dependent children are less likely to suffer the onset of depression/anxiety or high blood pressure, while someone who is separated is more likely to develop depression/anxiety.

And there are also some associations that reflect where you are from and where you live.

People from non-English speaking cultures are less likely to experience the onset of depression/anxiety or cancer, but they are more likely to develop high blood pressure and type 2 diabetes.

People in rural areas are less likely to develop depression/anxiety.

Highlighting the disadvantages faced by people with disabilities, disability is strongly associated with the onset of arthritis, depression/anxiety, heart disease and high blood pressure.

Indigenous Australians are more likely to develop heart disease or type 2 diabetes.

Surprisingly, the data reveals little significant association between poor diet and serious illness, other than highlighting that a failure to regularly eat fruit is associated with the onset of arthritis/osteoporosis.

However, being obese, and to a lesser extent being overweight, is associated with the onset of type 2 diabetes, heart disease and high blood pressure, while obesity is additionally associated with the onset of arthritis/osteoporosis.

Regular alcohol intake wasn't associated with the onset of any serious illness and actually reduced the likelihood of type 2 diabetes, but drinking a lot of alcohol (42 or more standard drinks a week) is associated with the onset of depression/anxiety.

Regular exercise (at least three times a week) is associated with a lower risk of developing depression/anxiety.

Most controversially perhaps, the data found no significant association between smoking and the onset of cancer.

However, University of Melbourne's lead economist on HILDA, Professor Roger Wilkins, says a more thorough analysis that includes a life-time history of smoking would likely tell a different story.

"There is a delayed onset to something like lung cancer, so young smokers won't necessarily be reporting cancer, and while this data takes in a four year period, it isn't going to catch people who gave up smoking some time ago," says Professor Wilkins.

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