The study of 3,600 people linking physical and psychological factors to heart and vascular diseases, is the longest of its kind, said Liisa Keltikangas-Jarvinen, professor of psychology at the University of Helsinki.

"A person's temperament determines what he considers stress and how he reacts or what kinds of physical reactions emerge during stress," Keltikangas-Jarvinen told a news conference.

While stress had been considered a factor in the illness for a long time, the concept of stress had been vague, she said.

"Temperament has not earlier been seen as a risk factor (of heart and vascular diseases)," Keltikangas-Jarvinen said.

Innate temperament, or the way people deal with situations, also explained why the same things were a challenge for some and a pain for others, and why in the same stressful situation some people got ill but others grew stronger.

"One cannot say what kind of stress is physiologically dangerous for people. It is how they feel the stress which determines whether they will get ill or not," she said.

An easily stressed person who was brought up in a stress-causing environment had an increased risk of falling ill with heart and vascular disease, Keltikangas-Jarvinen said.

One risk factor was a family environment where the child did not get emotional support, where he or she was not accepted, and where goals set for the child were extremely high.

Further risks were parents who were not satisfied with their lives -- such as career-oriented mothers who had cold and distant relationships with their children -- and who compensated for this dissatisfaction by working hard, she said.

There were also differences between the sexes on what kind of temperament types were risky and what were not.

Women who were dependent on social support did well but men who needed positive feedback were unable to see the physical warning signs their bodies were sending them during stress and faced a greater risk of heart disease.