Up to 20 percent of UK hospital appointments for heart or brain scans and other exploratory tests are taken up by patients suffering from excessive health anxiety or hypochondria, experts said on Thursday.

And while the problem is worsening - due in part to people with disproportionate health worries researching symptoms online in a phenomenon known as ?cyberchondria? - it can be effectively treated with psychological therapy, they said.

Presenting results of a study of the condition, researchers said hypochondriacs given an average of six sessions of cognitive behavioral therapy (CBT) over several months saw significant and sustained reductions in their anxiety levels.

Even five years later, long after the therapy had ended, those who?d had CBT were less over-anxious about their health than a control group who did not get the CBT.

Health anxiety is a common but often undiagnosed problem characterized by patients excessively worrying about being ill and fearing they may have a severe or rare unrecognized disease.

Symptoms can include chest pains or headaches that persist despite a doctor?s reassurance that there is no physical cause for concern.

Experts say health anxiety is a significant drain on health services and leads to unnecessary, invasive and expensive medical tests. Patients pay repeated visits to the doctor and to emergency departments, and frequently seek second and third opinions.

Researchers estimate the annual costs to Britain?s National Health Service of patients attending unnecessary tests and appointments could be as high as 56 million pounds ($73 million).

A World Health Organization study conducted in five countries and published in 2016 found health anxiety is not only a problem among the wealthy, but affects patients and health services in developing countries as well.

?Most sufferers attend medical practitioners in both primary and secondary care asking for help in searching for a physical diagnosis, so ignoring the mental core of the condition,? said Peter Tyrer, a professor of community psychiatry who co-led the study.

?We found health anxiety was common in those with other physical illness. So people ... would interpret minor symptoms as warnings ... (and) cut down on all their activities, create more suffering, and have their lives thrown into chaos.?

The study involved 444 people recruited from cardiology, endocrinology, gastroenterology, neurology and respiratory departments at five general hospitals in England. It was funded by Britain?s National Institute for Health Research (NIHR) and published in the NIHR Journals Library.