Hypochondriacs who worry needlessly that they might have a serious illness could be increasing their chance of getting one, according to new research.

The study looked at more than 7,000 people who were born in Norway in the 1950s. In all, 234 people in the group had had a heart attack or bout of acute angina by 2009, according to a paper in the journal BMJ Open.

But those who were anxious about their health, known as the 'worried well', were 73 per cent more likely to go on to develop heart disease than those who were not.

The researchers wrote: “These findings illustrate the dilemma for clinicians between reassuring the patient that current physical symptoms of anxiety do not represent heart disease, contrasted against the emerging knowledge on how anxiety, over time, may be causally associated with increased risk of [coronary artery disease].”

They stressed their findings “underline the importance of proper diagnosis and treatment of health anxiety”.

“[Our research] indicates that characteristic behaviour among persons with health anxiety, such as monitoring and frequent check-ups of symptoms, does not reduce the risk of [coronary heart disease] events,” they added.

The participants in the study filled in questionnaires about their health, lifestyle and education, as well as having physical check-ups that measures their blood pressure, weight and height between 1997 and 1999. Blood samples were also taken.

Their heart health was then tracked using national data on hospital treatment for heart conditions and death records. Anxiety was measured using a standardised scale called the Whitely Index.

The researchers stressed the study did not show a causal relationship between anxiety and heart disease, but supported current thinking that the former was harmful to health.

They also said people who feel anxious about their health might also suffer from other mental health problems such as depression, which could be the underlying problem.

Emily Reeve, a senior cardiac nurse at the British Heart Foundation, said: “It’s natural for people to worry if they feel they might be unwell.

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“But anxiety and stress can trigger unhealthy habits, such as smoking or eating badly, which put you at greater risk of heart disease.