A link between HRT and deafness has been found by researchers from the University of Rochester Medical Center (USA). Women on HRT increase their risk of deafness by 30%, they say.

Two groups of women, 32 in each, had their hearing measured in noisy areas. Their ability to process information was also examined.

The scientists had expected to see a positive result from hearing and HRT.

Tests were carried out on women aged 60-86. Each group was matched according to age and medical history.

The women were given a task of deciphering sentences while they listened to someone talking at the same time, this person was talking in a noisy place.

Women who had had HRT seemed to suffer more from Presbycusis - an age related form of deafness. With Presbycusis, the patient can hear lower sounds better than higher ones.

The researchers were at a loss to explain why HRT would have this effect.

One expert suggested that taking oestrogen (estrogen) and raising it to such a level may not be good for the brain. Oestrogen affects the level of sodium and potassium in the body. This affects nerve cell function.

The researchers also found that the HRT women were more likely to have problems processing information.

Some experts have had reservations about the study. One said that so far HRT has been accused of affecting everything but global warming.

A UK expert also noted that the USA uses a different form of HRT than the UK doctors prescribe. The Americans tend to use much higher doses of oestrogen.

Oestrogen is a natural hormone and used cautiously and for the right reasons is usually safe.

Most experts agreed that the study was too small and more should be carried out with more people.